BELFAST (UPI) -- Troops and police in riot gear patrolled the streets of Belfast Thursday and conducted house-to-house searches for suspects after sectarian rioting left dozens injured. More than 110 petrol bombs were thrown at police by Catholic and Protestant rioters. A Royal Ulster Constabulary spokesman said 39 police officers were injured in the running battles. Casualties among the rioters are not known, as most of those who took part in clashes with the police have gone into hiding and are unlikely to show up at state-run hospitals to seek medical treatment. The rioting capped several days of rising tensions between Catholic and Protestant sections of the community and came to a head after an explosion Wednesday afternoon near a so-called peace line that divides Catholic nationalist and Protestant homes. The blast caused no injuries but fueled an almost immediate flare-up in the area. About 600 pro-Britain loyalist Protestants were involved in the clashes with Catholics that led to hundreds of police officers being called to help control the mob. Police said its units fired eight of the new plastic bullets that were recently introduced in Northern Ireland. The apparently less-than lethal ammunition was deployed to signal a softening of the law enforcement agencies' handling of sectarian troubles. A senior police officer, Alan McQuillan, told news media, "What we had last night were simple naked sectarian riots with the police and the army in the middle attempting to keep the two communities apart." Jane Kennedy, appointed security minister in Prime Minister Tony Blair's new Cabinet that was named after this month's election, condemned the violence, saying, "The sight of large groups of thugs throwing petrol bombs and missiles at the police will have sickened all decent people in Northern Ireland." The sectarian violence is seen by analysts to be rooted in growing polarization between the Catholics and Protestants over the current stalemate in the peace process. The Protestants are angry over what they see as the government's soft approach toward Catholic nationalists and over concessions that are designed to increase Catholic representation in the police force. The Catholics, meanwhile, complain the security forces are not doing enough to protect their communities against protracted intimidation and attacks from loyalist groups. First Minister David Trimble, leader of the loyalist Ulster Unionist Party, has warned that the power-sharing administration that he heads faces collapse unless there is movement toward disarmament of the Irish Republican Army and other paramilitary groups on both sides of the sectarian divide.

The IRA is represented in the administration by two ministers elected as Sinn Fein, the IRA's political wing.