Yugoslav soldiers are reported to have set up checkpoints on all main roads into Montenegro, blocking imports of raw materials, confiscating humanitarian aid and stopping Westerners from entering.

"The regime in Belgrade wants to instal the Yugoslav army as a dictatorship power in Montenegro," President Milo Djukanovic told a local news agency.

Humphrey Hawksley: "President has angrily condemned army"

"A number of the most senior Yugoslav army officers in Montenegro are trying to place the army above the civilian institutions in our republic," he said.

Technically Montenegro controls its own borders and officials say this latest move is part of a policy to destabilise its pro-Western government.

President Djukanovic said the only legitimate authority in Montenegro was his multi-ethnic coalition government elected in 1997.

He accused the troops of serving the Belgrade dictatorship, violating the constitution and putting to shame the proud uniform of the Yugoslav army.

Machine gun bunkers

The soldiers are manning new checkpoints with machine gun bunkers about 10km (six miles) inside Montenegro and are stopping all vehicles going through.

Some foreign nationals without Yugoslav visas have been sent back to Croatia.

The UN has called for a protracted settlement of the crisis.

Its refugee agency, UNHCR, says it has enough relief supplies for three or four days by when it hopes a settlement willl have been negotiated. It has told staff not to push to get in in the meantime.

Dig at president

It is thought that this latest move against the pro-Western Montenegran Government could be aimed at Mr Djukanovic himself, says BBC correspondent Humphrey Hawksley.

The president is due in Britain in the next few days as part of a European diplomatic shuffle to find a formula for a democratic Yugoslavia after the crisis is over.