"The Secretary General strongly condemns the latest ambush in the Sinai on two mini-buses which killed 25 Egyptian police officers," a statement issued by Ban's spokesperson said. (Agencies)
The UN Chief expressed hope that "the perpetrators will be swiftly identified and brought to justice".
Militants on Monday ambushed two buses carrying police recruits from their base in North Sinai's Rafah city to their homes for a vacation. At least 25 policemen were killed and three wounded.
State news agency said the militants fired rocket-propelled grenades at the two buses. The gunmen forced the policemen to leave the bus and told them to stand in a line, and then shot them.
The UN Chief also said he was "deeply disturbed" by the reported deaths of 36 prisoners in police custody on Sunday as they were being transferred from one facility to another.
Ban called for a full investigation into this incident, the statement said.
A total of 36 members of the Muslim Brotherhood, from which Egypt's ousted president Mohamed Morsi hails, died in a riot when they were being transferred to a jail on Sunday.
Morsi was ousted by the army in July after only a year in office. The constitution was suspended and an interim government was established, as protests by Morsi's supporters turned violent across the country.
Last week, security forces cleared two camps of Morsi supporters in Cairo, and at least 866 people have been killed across the country since then, the Health Ministry said. "With such sharp polarization in Egyptian society, both the authorities and the political leaders share the responsibility for ending the current violence. They should spare no effort to swiftly adopt a credible plan to contain the violence and revive the political process," Ban said.
He said UN political affairs chief Jeffrey Feltman would hold discussions this week in Cairo "with a focus on how the United Nations can best support initiatives to restore peace and forge reconciliation in Egypt".
"The Secretary General strongly condemns the latest ambush in the Sinai on two mini-buses which killed 25 Egyptian police officers," a statement issued by Ban's spokesperson said.