A senior Hezbollah official vowed on Sunday to press ahead with street protests and other peaceful means to topple Lebanon's Western-backed government but said the group's plans would not be announced beforehand.

"There is no specific time frame and no final plans. There is a basket of ideas which we will use the way we see fit for achieving our goals," Sheik Naim Kassem, Hezbollah's deputy secretary-general, told the group's Al-Manar TV station.

His comments came after the government approved an international tribunal for suspects in the assassination of former Prime Minister Rafik Hariri, overriding the objections of Hezbollah and other government opponents.

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Six pro-Hezbollah ministers resigned earlier this month after talks with the government on giving the guerrilla group and its allies wider government representation failed.

Hezbollah has warned that the group would hold mass street protests seeking to force the government from power. Those protests were postponed after Tuesday's assassination of Industry Minister Pierre Gemayel, an anti-Syrian Christian leader.

Kassem reiterated the threat of mass protests Sunday but said the timing would be kept a surprise.

"This would make it more effective and also open the way for some sanity which we hope the other side will have before we reach a dead end," he said.

Kassem called on Prime Minister Fuad Saniora to resign, saying his government's meetings were now "worthless and unconstitutional" because the six ministers had resigned.

"We hold them (government) responsible for political instability and economic deterioration and any failures that may take place in administering the country," Kassem said. He added that Saturday's meeting in which the government approved the Hariri tribunal also was illegitimate.

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Formation of the tribunal heightens tensions in Lebanon, which is torn between opponents of neighboring Syria's influence here and its allies, including Hezbollah.

A U.N. investigation into the February 2005 truck bombing that killed Hariri and 22 others has said the killing's complexity suggested the Syrian and Lebanese intelligence services played a role in the assassination. Syria denies involvement.