Ahmedabad/Delhi/Jammu: A man has been arrested for sending the email threatening of a bomb blast in the city after the Delhi blast, police said here on Monday.

Manu Oza, the arrested man, allegedly sent the email to the Delhi police immediately after the blast outside the Delhi High Court on September 7. He had used the name of a most-wanted terrorist from US agency FBI's list.

"Oza (23), a resident of the Ghodasar area of the city, was arrested from Patan district yesterday where he had been staying with friends for the last five years," city Police Commissioner S K Sinha told media persons.

In the email, Oza had claimed the responsibility for the blast in Delhi, identifying himself as `Ali Saed El-Hoorie, a member of the Indian Mujahideen (IM)', Sinha said. The email was sent using a proxy server in Moscow.

Oza's was the third email to be received by Delhi police regarding the blast, of the total four. Oza had said in the email, in coded language, that next target would be Ahmedabad, which led to massive security strengthening here.

Union Home Minister P Chidambaram had said then that the mail seemed to be sent by an amateur, as the numerical code used in it was very simple.

"The email was sent with the intention to strike terror and create an atmosphere of fear.... Oza has been arrested under section 66 (F) of the Information Technology Act which carries maximum punishment of life imprisonment," Sinha said.

The Police Commissioner said that Ali Saed El-Hoorie, whose name Oza used, was on top of most-wanted list of the FBI. "Hoorie has a reward of USD 5 million on his head," he added. According the city crime branch which investigated the email, Oza is a standard 11th drop-out and he used to work in a call centre.

Five months ago, he had a fight with his father and left the home for Patan where he stayed with a friend, Rajkumar Yadav, and did some data entry job.

After Oza saw the Delhi blast news on TV, he allegedly decided to send a prank email to terrorise the people.

The cyber crime cell of the crime branch traced the email's origin from the Internet protocol (IP) address and found that it had been sent from Yadav's laptop, using a USB mobile broadband connection.

Oza had sent the email without Yadav's knowledge, using the Internet connection registered in Yadav's name. When Oza -- who was brought before mediapersons -- was asked why he sent the email, he said, "For fun and to get famous quickly."

Sinha said, "Oza told us that after the Delhi blast he got scared for his family in Ahmedabad and to alert the police he sent the e-mail. There is no evidence of him having link with a terrorists organisation."

Oza also told reporters that after leaving the home, he had learnt to hack computers and servers.

He claimed that he had been duped by a placement agent who had promised him a job in a call centre. "I was mentally disturbed because of my father," he added.

The city crime branch is also probing another email, similar to the one sent by Oza. Police believe that this email too is a prank, but they are not ruling out the possibility that it could have been sent by a genuine IM operative.

The first mail was received two hours after the blast and the Internet Protocol address was traced to Kishtawar in Jammu region, where police are interrogating youths.

Four persons detained in West Bengal for their suspected involvement in sending the second and fourth email were found not involved in the incident.

The mails, which were received since Wednesday, had sent the investigators into tizzy and they were trying to find out the senders to reach the perpetrators of the blast which claimed 13 lives and injured over 70.

Police sources in Delhi said they have received several calls and e-mails from abroad following the release of two sketches of suspects but none of them were of any help.

A senior police official said they received around ten calls from Delhi and one even from Kathmandu informing police that the sketches resembled some persons in their locality.

"Verification was done and those suspected were found not involved in the case," a senior police official said, adding that three of the four e-mails appeared to be identical.

The CCTV footages collected from Ram Manohar Lohia hospital where injured were admitted were being examined, the official added. Delhi Police is in touch with Anti-Terrorism Squads of various states, he said.

The email received by Delhi Police headquarters was claimed to have bounced from various Internet gateways with the server finally traced to Moscow.

The second mail was received by media houses on Thursday in Delhi and Mumbai claiming that the blasts were carried out by Indian Mujahideen. This mail has been traced to Kolkata.

The fourth mail was received on Friday.

2 kin of surrendered militants grilled

As investigators struggled for a breakthrough five days after Delhi High Court blast, two men considered close to surrendered militants were detained in Kishtwar in Jammu and Kashmir from where an e-mail purportedly sent by HuJi claiming responsibility was sent.

The number of people detained for questioning rose to 11 after Sadiq Ahmed and Abid Hussain, considered close to former militants Irshad Ahmed and Farooq Ahmed were picked up. The two former militants have already been detained.

The investigators probing the blast were vigorously pursuing the email sent from Kishtwar and believed that the other three emails claiming responsibility for last Wednesday's terror attack including the one purportedly sent by the Indian Mujahideen(IM) were pranks.

"Two close persons of surrendered militants have been picked up. They are under sustained interrogation after zeroing in on them", a senior police officer said in Jammu.

"Let us see what we get from them", he said. The purported HuJI email has been sent from Kishtwar itself and that is confirmed, he added.

Around 50 people from Kishtwar town, mostly students, have so far been questioned in connection with the Bangladesh-based terror outfit Harkat-ul-Jihad-Islami (HuJI) email claiming responsibility for the blast.

Official sources in New Delhi said investigators have brought the hard disks of the computers of the cyber cafe in Kishtwar to Delhi for forensic examination to find out whether the set time of any one of the computers was changed before sending the email.

A particular youth who allegedly sent the email was under the scanner, police said.

The call records of the youth were also being examined to find out whether he had received or made call to or from abroad and to or from Delhi before and after the blast which has claimed 13 lives.

Investigators believe that the other three emails, including the one purportedly sent by the Indian Mujahideen, were not sent by anyone having any links with the blast and appear to be pranks.