The United Nations on Wednesday warned that violent attacks on international peacekeepers and civilians in Sudan's conflict-torn Darfur region have been increasing while tens of thousands of people have been forced to flee the fighting.

U.N. officials and diplomats say the Sudanese government has become increasingly confrontational toward the United Nations and the West over the joint U.N.-African Union mission to Darfur (UNAMID), which Khartoum wants shut.

Deputy U.N. peacekeeping chief Edmond Mulet told the 15-member Security Council that there has been negligible progress in peace efforts for Darfur, adding there was a worrying rise in attacks on UNAMID.

U.N. chief Ban Ki-moon's latest progress report on the force said there were 60 "incidents and hostile attacks against UNAMID" in the three months to May 15, compared with 46 in the previous quarter.

Mulet noted that the second phase of the government's "Decisive Summer" military campaign to end armed rebellions has caused a new wave of displacement across Darfur. He said humanitarian organizations estimated at least 78,000 newly displaced this year, while the U.N. has unverified reports of 130,000.

Sudan's Deputy U.N. Ambassador Hassan Hamid Hassan told the council that the violence and displacements were mainly due to tribal clashes and attacks by rebels, not government forces. He added that the government's operations have brought stability to Darfur.

Late last year Khartoum ordered UNAMID out of the country after it began investigating an alleged mass rape by Sudanese soldiers in Darfur. The government denies any wrongdoing by its soldiers and has prevented UNAMID from investigating.

In addition to a 12-month extension of the force's mandate, Ban recommends a gradual drawdown based on the ability of the government and armed groups to make progress on peace.

Several council diplomats said that there should be no swift withdrawal of UNAMID given the current violence.

"It would be irresponsible ... to give in to the demands of Khartoum for a premature exit or even partial withdrawal," a U.S. official said on condition of anonymity.

"We're not going to leave Darfur to the mercy of what is a very repressive regime in Khartoum," a diplomat added.

UNAMID has faced allegations by Western powers it has not done enough to protect civilians and withheld information on the scale of violence against civilians and peacekeepers by the Sudanese army and allied militias. U.N. officials say UNAMID has been working to improve its performance.