SIX RAF Jaguar ground attack aircraft left for the Balkans last night to reinforce a tough political message designed to force President Milosevic, the Serbian leader, to stop any further Serbian attacks in the Kosovo province.

Defence Secretary George Robertson said they were being deployed to take part in Nato ''live fire'' exercises near the province, where Serbian forces have been engaged in a purge against ethnic Albanians.

However, he stressed that unless President Milosevic called off the operation which has forced tens of thousands to flee their homes, the aircraft would be prepared to take action for real.

After a meeting of G8 Foreign Ministers and the Foreign Ministers of Canada and Japan in London yesterday, Foreign Secretary Robin Cook claimed President Milosevic must take immediate action to ''prevent any further deterioration'' in the situation.

The Serbian leader has been faced with an ultimatum from the Foreign Ministers, who have made his meeting with President Yeltsin in Moscow on Tuesday the deadline for the violence to end, or face a military onslaught.

Russia, however, yesterday refused to back Nato's show of strength. Defence Minister Igor Sergeyev met all 16 Nato Defence Ministers in Brussels and said later: ''Currently, we have to focus on political measures.''

Nato hopes that President Yeltsin will drive home the seriousness of their threats when he meets Milosevic next week.

Mr Cook warned: ''If President Milosevic does not agree, he must not be in any doubt about the consequences. In the event of President Milosevic failing to carry out the action plan we have mapped out, then we will consider further measures which will be different in quality and will include those measures that may be authorised by a UN security resolution.''

Mr Cook added: ''He will be making a grave mistake if he imagines the international community will be as slow to respond as it was in Bosnia. We have learnt our lesson. We hope that President Milosevic has learnt that lesson too and will listen to the clear, loud and united message of the G8 countries.''

Announcing the deployment of the RAF Jaguars last night, Mr Robertson said the exercise was intended to underline the message to the Serbian president that Nato was prepared to use military force.

He said: ''Mr Milosevic must understand that diplomacy to end the escalating Kosovo violence is being backed up by the threat of force. This is not just Defence Ministers rattling sabres - it is time for Belgrade to get the message that Nato means business.''

The Jaguars from RAF Coltishall in Norfolk will fly to the Gioia del Colle airbase in Italy within the next 24 hours ready to take part in possible Nato air exercises over Albania and Macedonia.

An RAF Tristar air tanker is also heading to Ancona in Italy from RAF Brize Norton to take part in the operation.

Mr Cook, who did not rule out the possibility of President Milosevic being a candidate before a war crimes tribunal, made clear they expected immediate action. He said: ''Not all of it would be done by tomorrow, but he can make a start tomorrow. We expect rapid progress.''

Mr Cook also had harsh words for India and Pakistan which he claimed had done nothing but damage to themselves and to the world community by carrying out nuclear tests.

He said: ''They have both weakened their economies, they have both lowered their standing in the world and they have done nothing for their own national securities. And in the process they have undermined the global efforts to stop nuclear proliferation. Those test programmes have been a lose, lose development all round.''

Mr Cook made it clear Britain, backed by the international community, did not want confrontation with the people of India and Pakistan, but they would firmly confront the threat of nuclear proliferation.

He pointed to the wider group of countries which had discussed their growing concern about developments on the Indian subcontinent, which included Argentina, Brazil, South Africa, and the Ukraine ''countries who have announced and carried out decisions to abandon the nuclear options''.

Mr Cook claimed it was these countries, not India and Pakistan, which represented the trend in the modern world and were particularly well qualified to consider how best to persuade India and Pakistan to join the present path.

The Foreign Secretary announced that a task force of experts and officials, co-ordinated from Britain, would be set up to work towards ''ways in which we can bring India and Pakistan back into the global world of non-proliferation''.

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