The German Chancellor, Mr Gerhard Schroder, said that Russia's diplomatic efforts had brought closer the prospect of a political settlement to the Kosovo crisis. But he insisted that NATO's key demands must be met before the bombing campaign against Yugoslavia could be halted.
In Bonn after meeting the Russian special envoy, Mr Viktor Chernomyrdin, the Chancellor said Yugoslav forces must begin to withdraw from Kosovo before any ceasefire.
"If the withdrawal begins and is verifiable, it would make sense to consider a limited halt to air strikes," he said.
Mr Chernomyrdin said he believed that Belgrade was moving towards accepting the deployment of an international peacekeeping force to supervise the return of ethnic Albanian refugees to their homes.
But he added that the United Nations, as opposed to NATO, must assume the leading role in any such force.
"Everything in the Balkans must be done under the leadership of the UN," he said.
Germany hopes that Moscow's diplomatic initiative will lead to a UN Security Council resolution approving the deployment in Kosovo of an international peacekeeping force with a substantial Russian element.
Many members of Mr Schroder's centre-left coalition are increasingly unhappy at the continuation of NATO's military action against Yugoslavia and are impatient for a political solution to the crisis.
The Chancellor played down the prospect of an early end to air strikes, but agreed that Mr Chernomyrdin's intervention had brought peace closer.
"Naturally we are working from the basis of the position that we established at the NATO summit in Washington and we see a certain coming together," he said.
In Brussels, NATO officials faced another uncomfortable ordeal. In a strange combination of events, two states which have given support to the NATO operation became victims of that operation on the same night.
The weather was good on Wednesday, making it possible for 30 missions to be flown. The attacks were concentrated on the Montenegro airport at Podgorica, which was hit very heavily.
But one flight went off course and dropped a bomb on Sofia, capital of Bulgaria, which has given NATO the right to use its air space. The bomb hit an apartment building in the centre of the city, and yesterday NATO admitted responsibility. No one was hurt in the incident.
"This was not intentional and we regret any damage this may have caused," NATO spokesman Mr Jamie Shea said.
"There are any number of reasons why a missile can go off course," NATO's Gen Giuseppe Marani admitted. "We are making sure of our procedures and doing everything we can to prevent any further accidents of this kind."
As soon as NATO heard the accident had taken place, the Bulgarian ambassador to Brussels was contacted by the alliance. A full investigation is taking place in co-operation with the Bulgarian government, which has reaffirmed full support for the oil embargo proposed by NATO to prevent supplies entering the port of Bar in Montenegro.
Gen Marani said NATO "would have preferred not to have attacked sites in Montenegro, but Podgorica airfield is becoming an important operating location for the FRY (Federal Republic of Yugoslavia) air force. Aircraft driven from their main bases by NATO attacks are using the airfield as a dispersal base.
"As previously stressed many times, there will be no sanctuary for forces engaged in and supporting the ongoing aggression in Kosovo."
There were multiple strikes against the airfield in Montenegro, Gen Marani said. "These were precision surgical strikes that were highly sensitive to avoid damaging civilian infrastructure such as the runway and terminals," he added.
But following a night of fear, with fires lighting up the skies, the government in Montenegro, which has supported the NATO operations up to now, held an emergency meeting to see how to deal with this new intensification. It also appealed to NATO to stop the bombing.
The 30 NATO strikes of Wednesday "successfully targeted" airfields, petroleum facilities, lines of communication and field forces, Gen Marani said. They caused "significant impact and will continue," he added.
He also noted: "The weather forecast is good for the next few days."
Tim O'Brien adds:
The Irish journalist, Maggie O'Kane, has been asked to leave Yugoslavia by the authorities there. Ms O'Kane, who works for the Guardian, has been interviewing members of opposition parties in Yugoslavia.
No official reason for the expulsion has been given. Ms O'Kane was last night said to be making arrangements to travel overland to Hungary.
Reuters adds:
Yugoslavia said yesterday it was suing NATO countries involved in the five-week-old bombing campaign of its territory at the International Court of Justice in The Hague.