A senior Libyan official Thursday accused NATO of intensifying its bombing campaign and backing foreign mercenaries to lay the groundwork for an advance by rebels trying to topple Libyan leader Muammar Al Qathafi's regime.

Deputy foreign minister Khaled Kaim told The Associated Press in an early morning interview that the alliance's increased bombings represent the "final phase" of the air campaign. But he said the push will fail and that civilians will be the ones to pay the price.

Kaim went on to say that NATO targeted police checkpoints in the Nafusa mountains southwest of Tripoli ahead of a rebel advance toward the village of Qawalish, which rebel fighters claimed they seized Wednesday. They were later pushed back by government troops, he said.

He further pointed out that a fuel depot in the key eastern oil town of Brega was also destroyed.

In its reaction NATO said it hit equipment used to refuel government military vehicles.

Kaim said that NATO's intensified campaign, is focused on targeting civilian infrastructure and police checkpoints, and providing additional weapons to rebel fighters.

"The aim of these attacks is to help the rebels to advance. But I assure you, it will be another failure for them," he said.

Kaim accused the rebels of using Colombian mercenaries funded by the West and its Arab allies to fight their battles. He said that Libyan forces have evidence that these mercenaries have joined the rebel fighters trying to advance toward the capital Tripoli from the western rebel-held city of Misurata.

Some of the Colombian fighters had been killed in clashes near Misurata on Wednesday, Kaim said. He would not not immediately provide evidence to substantiate the allegation, but he said it would soon be shown to journalists based in Tripoli.