His chances of success have been complicated by Thursday's indictment of Yugoslav President Slobodan Milosevic for alleged crimes against humanity.

Mr Chernomyrdin warned further talks would be pointless if Nato did not stop the air strikes.

But Nato forces continued to pile on the pressure, again recording the heaviest 24 hours of bombarding against Serb forces and infrastructure in Yugoslavia. Three civilians were reported killed.

The BBC's Bridget Kendall: "The chances of a peace deal look far more uncertain"

Nato military spokesman General Walter Jertz signalled the strikes would be stepped up still further after a record 792 missions flown over the past 24 hours.

"Let me tell you what Milosevic already knows - for the next five days the weather is on our side," said Gen Jertz.

He said there would be more successful strikes on military targets in the next few days.

'People are dying'

Mr Chernomyrdin expressed his concerns as he left for Belgrade: "We have been talking for over a month now, but, nevertheless, there is no result at all. Nato's bombing of Yugoslavia is on the increase and people are dying.

"If things continue this way, talks will become meaningless," he added.

The Russian envoy warns that, unless the air campaign is halted soon, he will advise President Yeltsin to:

• Suspend Russian participation in the negotiating process

• End all military-technological co-operation with the West

• Veto United Nations resolutions on Yugoslavia

Return trip

But Mr Chernomyrdin has also announced he is to return to Yugoslavia next week with European Union representative, Finnish President Martti Ahtisaari.

The pair have been taking part in tri-partite talks with US Deputy Secretary of State Strobe Talbott, although there has been no breakthrough on the make-up of a potential peacekeeping force.

Four Serb anti-aircraft installations were hit on Wednesday

A Turkish general said on Friday that Turkey would join any ground forces sent into Yugoslavia if ordered to by Nato.

The Russian envoy to the Balkans said the indictment of President Slobodan Milosevic for war crimes would not make a difference to the talks.

"Slobodan Milosevic is a legitimately-elected president of Yugoslavia. We dealt, are dealing and will be further dealing with him," he said.

Food parcels confiscated

Meanwhile the Yugoslav army has been stopping aid reaching Kosovo and confiscating food parcels, said Nato spokesman Jamie Shea.

Of 12 humanitarian convoys in Yugoslavia on Friday, not one was in Kosovo, he said, and 28 lorries were being held up at the Montenegran border in a dispute over documents.

"A lot of the food has been directly confiscated by the Yugoslav army," he said.

The United Nations mission that visited Kosovo this week also reported seeing World Food Programme food parcels on sale in a shop.

Heavy bombardment

On the 67th night of strikes, Nato attacked military installations in and around Belgrade and Nis, in southern Serbia.

(Click here to see a map of latest Nato strikes)

The Serb authorities said 30 bombs fell in Nis, hitting a bridge, a factory, the airport, the main road to Belgrade and the industrial zone.

Three people died when a bomb fell in a residential area of Aleksinac, local media said.

Belgrade lost power for several hours on Thursday evening.

Five indicted

The BBC's David Shukman: A legal noose is being tightened around him

Chief UN War Crimes Prosecutor Louise Arbour said five indicted Yugoslav officials were being held personally responsible for their role in the deportation of 740,000 Kosovar Albanians and the murder of 340 identified Kosovar Albanians.

Mr Milosevic is the first sitting head of state to be indicted by the tribunal. If he is brought to trial and convicted he will face a maximum life sentence.

• Refugees film ethnic cleansing
• Chernomyrdin threatens Russian withdrawal
• Plug pulled on Serb satellite TV
• Analysis: Indictment raises the stakes
• Serbs shell Albanian border

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