JERUSALEM (AP) _ A U.N. spokesman today denied reports of a firefight between Norwegian peacekeeping troops and Israeli-backed militiamen in southern Lebanon.

On Friday, U.N. sources in Lebanon said the peacekeepers clashed with a force of the Israeli-trained South Lebanon Army that had kidnapped a Lebanese civilian in the town of Shibaa.

The sources said the firefight, involving automatic rifles as well as rocket-propelled grenades, started after a six-man Norwegian patrol tried to prevent the kidnapping. No injuries were reported.

Timor Goksel, spokesman for the United Nations Interim Force in Lebanon, denied today there was an exchange of fire.

Goksel said a unit of the South Lebanon Army's security service entered Shibaa to grab a wanted man. After the Norwegian peacekeepers intervened, a militiaman fired a rocket-propelled grenade over their heads, causing no injuries or damage, Goksel said.

He said the Norwegian troops did not return fire. The militiamen withdrew deeper into the Israeli-controlled security zone, taking the detained man with them, he said.

The 702-strong Norwegian battalion serves with the nine-nation U.N. force, which patrols a narrow buffer in the southern provinces of Lebanon separating the security zone from the rest of Lebanon.