JAKARTA, May 17 (Reuters) - Three U.N. experts will start an inquiry in Indonesia on Wednesday into a rampage by pro-Jakarta gangs in East Timor that killed about 1,000 Timorese after an independence vote in 1999.

An Indonesian Foreign Ministry official said on Tuesday that the three experts appointed by U.N. Secretary-General Kofi Annan earlier this year would stay until May 20. It was unclear if any of the experts had arrived.

Annan's move to set up a team to review what happened in 1999 has irritated Jakarta, which in December had announced plans to set up a separate joint truth and friendship commission with East Timor to try to put the slaughter behind them.

Sensitive to accusations it has not properly accounted for the violence that swept East Timor in 1999, Indonesia has labelled the U.N. commission as "redundant" and had initially refused to grant its members visas to visit.

The Foreign Ministry official indicated the U.N. experts were expected to help the Indonesia-East Timor truth commission.

"There is no resistance. But in the beginning when the (U.N.) commission was set up we said it was unnecessary because we have the CTF," the official said, referring to the joint truth commission.

"The secretary-general (Kofi Annan) said this team was set up to help the truth and friendship commission...so among other things they are going to discuss how the U.N. commission can help it."

The three U.N. experts are an Indian judge, a Japanese law professor and a Fijian lawyer.

U.S. PRESSURE

A U.N. official who declined to be identified has said that Annan, during a trip to Jakarta last month, raised with President Susilo Bambang Yudhoyono the Indonesian government's refusal to allow the team members to visit.

In early April, the experts visited East Timor.

The rampage in the former Portuguese colony, carried out by gangs supported by elements in the Indonesian army, was triggered by a referendum in which East Timor voted to break free from Jakarta after 24 years of brutal military rule.

An Indonesian special human rights court set up after the violence tried 18 Indonesian military, police officers and civilians over the violence. Most were acquitted.

In setting up the separate truth commission, which was formally launched in March, Indonesia and East Timor had said they hoped to head off the parallel initiative by Annan.

The United States said this month Indonesia would not enjoy full military ties with Washington until it accounted for the violence in East Timor, saying this included cooperating with the U.N. team.

Washington severed military ties after the sacking of East Timor in 1999, and has only begun to revive such cooperation.

East Timor President Xanana Gusmao, a former rebel leader who has sought to patch up ties with his giant neighbour, has said he hoped the truth commission would satisfy the international community that justice was being
sought.

It will have no power to punish anyone found responsible for abuses and will start work in August, Indonesia has said.

Mainly Catholic East Timor finally became independent in May 2002 after two-and-a-half years of U.N. administration following the referendum and destruction of most of the tiny territory.