The resolution, drafted in emergency session, said the changes approved by the Yugoslav Parliament on Thursday had been passed "without the participation of legitimate and legal representatives of Montenegro".

Correspondents say the move is a further step towards independence for Montenegro - Serbia's junior partner in the federation - but it falls short of a full declaration.

There is widespread concern that if Montenegro were to declare outright independence, Mr Milosevic would intervene militarily.

'Illegal'

In a statement released on Thursday evening, Montenegrin President Milo Djukanovic, said: "By changing the Yugoslav constitution in a non-democratic and almost illegal way, the Belgrade regime has finally toppled the constitutional system of the country and brought its fate into question."

The president's senior adviser, Miodrag Vukovic, put his country's position more bluntly.

"The Montenegran Parliament is obliged to publicly announce that it does not recognise such acts and that it will not respect them," he said.

Final move

Balkans analyst Gabriel Partos told the BBC: "Serbia is unlikely to let Montenegro go without a fight.

"There is also a substantial minority of pro-Belgrade supporters in Montenegro who would also not want Montenegro to go, so there is always the chance of civil war."

Mr Milosevic appears to have taken a calculated gamble by forcing his arch enemy, President Djukanovic, to come down off the fence over staying in the federation.

Critics say Milosevic wants to become president-for-life

In the last year, Mr Djukanovic has defied Belgrade by maintaining cordial relations with the West, and introduced the German mark as a parallel currency.

But despite continuous pressure from some of his allies in the Montenegran Government, Mr Djukanovic has until now been reluctant to make the final move and call a referendum on independence, fearing a possible armed conflict with Mr Milosevic's supporters.

War crimes charges

In the emergency meeting of the Montenegrin Parliament, deputies will try to decide how to react to the changes.

The BBC's Central European Correspondent Nick Thorpe said the most likely outcome would be the announcement of a moratorium on all relations with Serbia.

Deputies applaud the constitutional changes

The Yugoslav president is currently elected by parliament and cannot run twice.

Opposition deputies in Belgrade also condemned the changes.

"This is what we call the legalisation of tyranny," said Tomislav Jeremic of the opposition Serbian Renewal Movement.

The Serbian Renewal Movement, one of the three main opposition groupings led by Vuk Draskovic, boycotted the debate in the lower house.