Cairo: Defying ceasefire, defiant Gaddafi hit out at the Western forces and pushed into the rebel-held city of Benghazi on Saturday. Calling Barack Obama as "our son", Libyan leader Muammar Gaddafi sent a message to the US President defending his decision to attack the rebels fighting to overthrow him.

Gaddafi (68) also wrote a letter to the French and British leaders, and the UN Secretary General, saying the Security Council resolution was "void" and violated the UN charter, warning them that they would "regret" any intervention. "Libya is not for you, Libya is for the Libyans," he said.

Details of Gaddafi's letters were released by the Libyan government spokesman at a news conference in Tripoli.

Defending his decision to attack rebel cities, Gaddafi told Obama, "Al Qaeda is an armed organisation, passing through Algeria, Mauritania and Mali. What would you do if you found them controlling American cities with the power of weapons? What would you do, so I can follow your example?"

Trying to strike a personal note, Gaddafi prefaced his letter saying, "To our son, his Excellency, Mr Baracka Hussein Obama. I have said to you before, that even if Libya and the United States of America enter into a war, God forbid, you will always remain a son. Your picture will not be changed."

In his letter to Nikolas Sarkozy, David Cameron and Ban ki Moon, Gaddafi said, "Libya is not yours, Libya is for the Libyans. The Security Council, their resolution is void because it is not according to the charter to interfere with the internal affairs of the country."

“You have no right. You will regret if you get involved in this, our country. We can never shoot a single bullet on our people, it is Al Qaeda organisation."

Gaddafi defies ceasefire

Meanwhile, reports about Gaddafi’s violation of the truce came in. It was reported on Saturday that the rebel-stronghold of Benghazi came under attack from ground and air with explosions rocking the city despite a ceasefire announced by Muammar Gaddafi forces. This prompted a warning by the US that the Libyan leader was violating the truce.

Two unidentified jets carried out bombing raids on the Libya's second largest city and a bastion of opposition after reports of night long trading of gunfire, raising a new possibility of military action by the US and its allies.

A reporter in the city said that one of the attacking aircraft had been downed by ground fire and was flying inspite of a UN no-fly resolution.

While the rebels claimed that Gaddafi's forces were not holding to their unilateral ceasefire and continuing their advance on the town, the Libyan government said that its forces had stopped their offensive short of the city.

A new channel quoted Libyan Deputy Foreign Minister Khalid Kaaim as claiming that the government forces were sticking to the ceasefire.

"The armed forces are now located outside the city of Benghazi and we have no intention of entering," Kaaim told reporters.

Blaming the rebels for continuing their attacks on Gaddafi forces, the Libyan Minister called for immediate deployment of foreign observers from Turkey and China, saying otherwise "the accusation and counter-accusation will not stop."

Al Jazeera said contrary to the claims by the rebels, Gaddafi's forces were reported to be just 50 kilometers from Benghazi towards the south of the city.

At the UN, Susan Rice, the US envoy to the world body, accused Gaddafi's forces of violating the truce announced by them.

"Gaddafi is violating the ceasefire imposed by the UN Security Council resolution," she said, adding "We don't believe the military action has stopped."

The reports of fresh fighting in strife-torn Libya came as the US President Barack Obama delivered a blunt ultimatum to the Libyan leader threatening military action if he ignores non-negotiable UN demands for a ceasefire and a retreat from rebel bastions.

"Gaddafi must stop his troops from advancing on Benghazi, pull them back from Ajdabiya, Misurata and Zawahiya and re-establish water, electricity and gas supplies.

Leaders from Britain, the US, France and Arab nations are due to meet in Paris later in the day to discuss military action under the new UN resolution.

A NATO's top decision making body is also meeting in emergency session in Brussels to review the military action plans for a no-fly zone over Libya.

The meeting comes amid reports that NATO council is expected to issue the order to launch the operation over the weekend.