In another sign that Muammar Qaddafi's regime was redoubling efforts to beat back resistance in its stronghold of western Libya, NATO warships intercepted several boats laying anti-shipping mines outside the harbor of the opposition-held city of Misrata.

The Dhuheiba border crossing between Libya and Tunisia has been a flash point in recent days. On Friday, there were different accounts of what exactly happened there.

Ismail Al-Wafi, a Dhuheiba resident, said the Libyan forces fired indiscriminately as they drove into town, setting off clashes. Three Tunisians were injured. He said Dhuheiba residents clashed with the Libyans and Tunisian troops eventually captured some and took their weapons.

Another witness said Libyan troops clashed with Libyan anti-government fighters in Dhuheiba before they were defeated by Tunisian troops. Some of the Libyans were captured and the others chased out, said the witness. "Qaddafi forces are no longer in Dhuheiba. They were defeated," he said.

The Tunisian news agency TAP said Tunisian forces fired in the air, but did not clash with Libyan troops.

The Tunisian Foreign Ministry issued an angry statement. "Given the gravity of what has happened ... the Tunisian authorities have informed the Libyans of their extreme indignation and demand measures to put an immediate stop to these violations," the statement said.

It was unclear why the Libyans entered Dhuheiba in the first place. One witness said they were fleeing from anti-government fighters who had recaptured the border crossing earlier Friday. An Associated Press Television News crew saw two bodies of Libyan troops near the crossing Friday.