VIENNA, Austria (AP) _ An explosion on Friday ripped a hole in the office door of Saudia, the state-run airline of Saudi Arabia, but there were no casualties.

Investigators later found a hand grenade in front of the state-run Kuwait Airways Corp. office on the floor beneath Saudia. Authorities said the grenade was defused.

The building, which houses offices of other airlines and the Vienna bureau of United Press International, is opposite the state opera on the Ringstrasse boulevard.

Police said they did not know what sort of device caused the explosion. They said damage was slight.

There was no immediate claim of responsibility.

A woman employee who refused to be identified said three Saudia employees were in the office when the afternoon explosion occurred but none was hurt.

Witnesses said the corridor was strewn with glass shards. Reporters were not allowed to enter the building.

Police temporarily closed two nearby roads, but no arrests were reported. The blast occurred while the Saudi interior minister, Prince Nayef Bin Adulaziz, was on an official visit in Austria. He visited a rural police unit outside Vienna and held talks on fighting international terrorism Friday.