* U.N. Human Rights Council opens main annual session
* Turkey condemns Syrian government attacks on civilians
* Britain, Switzerland urge referral of Syria to ICC
* Rights boss Pillay regrets Security Council failure
By Stephanie Nebehay
GENEVA, Feb 25 (Reuters) - Turkey accused Syria on Monday of attacking Syrian towns with bombing, shelling and Scud missiles and called at a meeting of the U.N. Human Rights Council for perpetrators of atrocities to be brought to justice.
Britain and Switzerland urged the United Nations Security Council to refer war crimes in Syria to the International Criminal Court (ICC) for prosecution.
"The (Syrian) regime has lost its legitimacy. It is no longer governing. It is surviving by oppression, terror and massacres," Turkish Foreign Minister Ahmet Davutoglu declared.
"Today, the regime is waging a brutal war against the Syrian people through indiscriminate air bombardments and Scud missile attacks against urban areas," he said. "We have to make sure that all perpetrators will not go unpunished."
Torture of detainees is systematic, Davutoglu added.
An estimated 70,000 people have been killed in the nearly two-year-old conflict between President Bashar al-Assad's forces and rebels fighting to topple him, the United Nations says.
More than 900,000 Syrian refugees have fled abroad, including some 185,000 in 17 camps in neighbouring Turkey.
U.N. investigators said a week ago that Syrian leaders they had identified as suspected war criminals should face the ICC.
"The atrocities in Syria remain foremost in our minds. We cannot stand by and allow this situation to continue," Baroness Sayeeda Warsi, a minister in Britain's Foreign Office, told the Geneva forum. "Those responsible for the worst violations and abuses must be held to account, including through the ICC."
Swiss Foreign Minister Didier Burkhalter acknowledged that the Security Council remained divided on whether to refer Syria to the ICC, but said that pressure to do so was building.
"Combating impunity is indispensable if we are to build sustainable peace in Syria and elsewhere," he told the forum.
Russia and China, both permanent council members, have shielded Syria by blocking Western efforts to take stronger U.N. action, such as sanctions, against Syria to try to end the war.
More than 50 countries asked the Security Council last month to refer the Syria crisis to the Hague-based ICC to send a signal to Syrian authorities. The letter, sent by Switzerland, was signed by Britain and France, but not the United States.
U.N. human rights chief Navi Pillay criticised the council on Monday for not referring the Syria crisis to the ICC "despite the repeated reports of widespread or systematic crimes and violations". (Additional reporting by Emma Farge; Editing by Alistair Lyon)