"There is no magic breakthrough in Russian envoy Viktor Chernomyrdin's talks with Milosevic," a senior White House official said on condition of anonymity after Clinton's meeting with the former Russian prime minister.

The quest for a diplomatic solution to the Kosovo tangle was "very complicated", Chernomyrdin said after briefing Clinton and Vice-President Al Gore on his last week's talks with Milosevic.

Chernomyrdin had yesterday said that he was closer to a diplomatic solution to the Kosovo conflict after talks with Clinton. "We got closer to a diplomatic solution," Chernomyrdin had told reporters at the White house. Chernomyrdin had brought Clinton a letter from Russian President Boris Yeltsin which he has said contained concrete proposalsto end NATO's air war against Yugoslavia.

When he was asked if Clinton indicated that he might be willing to halt the bombing, an optimistic Chernomyrdin had replied, "Naturally." The Russian envoy said that the circumstances under which NATO might stop bombardment was "the main issue."

Clinton yesterday had dangled on the possibility of a pause in NATO's air strikes and said he would be willing to negotiate the composition of an international peacekeeping force in Kosovo.

However, speaking at a press conference along with Japan's premier Keizo Obuchi on Monday, Clinton said, "our conditions for ending the bombing are not complicated."

"We have said under the right circumstances we would be willing to have a bombing pause, but we would need acceptance of the basic principles and at least beginning of withdrawal of Serbian forces," he said.

He reiterated NATO demands that Belgrade allow Kosovar refugees to return, withdraw Serb forces from the region and agree to deploy an international securityforce there before airstrikes that entered the 41st day today are halted.

Immediately after his talks with the Russian envoy, Clinton met American civil rights leader Rev Jesse Jackson and lauded his role in securing the release of three US soldiers held captive by Yugoslavia.

The US President, however, rejected Jackson's call for cessation of NATO air strikes saying: "...Our campaign cannot stop until Milosevic shows he is ready to end the nightmare for the people of Kosovo."

The White House also turned down Jackson's proposal of a face-to-face meeting between Clinton and the Yugoslav President.

Britain also said NATO needed "clear and unambiguous" proof of troops withdrawal from Kosovo before suspending its air raids.

Meanwhile, reports from Belgrade said NATO planes fired four missiles at the southern Serbian town of Vranie today.

"Early on Tuesday morning NATO aggressors fired four missiles to the northeast area of Vranie," official Yugoslav news agency Tanjug said. NATO planes also bombed theMorina border pass Albania and Serbia in western Kosovo.

The alliance, however, denied its warplanes were responsible for the bombing on a bus near Pec, Kosovo, in which Serbian authorities claimed 17 people were killed.

NATO began its air strikes against Yugoslavia on March 24 in a so-far futile effort to stop a Serb offensive against ethnic Albanians in Kosovo.