(adds delay to Senate vote, paragraph 12)

By Joe Bavier

KINSHASA, April 14 (Reuters) - Congo's main opposition party, whose leader left the country this week after fighting in the capital, has suspended participation in the lower house of parliament, citing security concerns.

Members of the Movement for the Liberation of Congo (MLC) of defeated presidential candidate Jean-Pierre Bemba have complained of harassment and intimidation by security forces since government troops routed his soldiers on March 22-23.

The former rebel chief went to Portugal on Wednesday for medical treatment and the public prosecutor has asked the Senate upper house to lift the immunity he enjoys as a member so he can face charges over the violence, in which hundreds were killed.

"We, the elected representatives of the opposition, consider the current climate of permanent insecurity does not permit us to work in the serenity that the mandate of a member of parliament requires," MLC National Executive Secretary Thomas Luhaka said in a statement seen by Reuters on Saturday.

"This is why ... we feel obliged to suspend, effective now and until further notice, our participation in the work of this (National) Assembly, until proper security conditions are established." An MLC spokesman said the statement had been read to a joint session of parliament late on Friday.

Luhaka said the decision followed the looting by a dozen members of the Republican Guard of the home of an MLC parliamentarian on Thursday night which he said was part of a "targeted and programmed operation" against MLC members.

Congo's U.N. peacekeeping mission last week denounced acts of aggression and intimidation against opposition figures.

"AUTHOR OF VIOLENCE"

Bemba lost a run-off vote to President Joseph Kabila last year in the nation's first free elections in over 40 years, meant to crown a years-long peace process after a 1998-2003 war.

Last month's fighting started when Bemba's bodyguards, numbering several hundred fighters, defied a government order to disarm under a plan to cut his security detail to 12 policemen.

On Tuesday, public prosecutor Tshimanga Mukeba requested permission from the head of the country's new Senate to prosecute Bemba as the 'intellectual author' of the violence in the capital, which is believed to have left up to 600 dead.

The charges against him include threatening internal state security, murder, armed robbery and destruction of property.

An MLC spokesman said the party's suspension of National Assembly activities did not affect senators, who are expected to vote on whether to lift Bemba's immunity once the Supreme Court approves bylaws for the Senate, which could take another week.

The provisional Senate head agreed on Monday for Bemba, who had been holed up in the South African embassy in Kinshasa since last month, to go abroad on the condition he returns in 60 days.

Bemba won more than 40 percent of the vote in an October run-off vote, but his Union of the Nation coalition, which includes the MLC, took only 18 of 108 Senate seats and around 100 seats in the 500-member lower house.

AlertNet news is provided by