The prime minister said he was prepared to negotiate directly with representatives of several thousand miners who are marching towards the capital, Bucharest, in a protest over pay and job losses - but only if they return to work.

"The credibility and the future of Romania is at stake," Mr Vasile said in a live television broadcast. "We cannot accept force or blackmail."

He said the government's foreign debt commitments made it impossible to meet the miners' demands for a 35% wage increase and the reopening of two closed mines.

The Romanian news agency Rompres quoted him as saying he was willing to participate in the negotiations, if the miners resumed work.

Europe Reporter Nick Thorpe: "Freezing temperatures and riot police"

Romanian President Emil Constantinescu earlier held an emergency meeting of senior politicians to discuss the protest, which began in the mining town of Petrosani, 350km from Bucharest.

Stormed roadblocks

Strike leader Miron Cozma: "The authorities cannot deprive us of our legs"

On Tuesday between 7,000 and 10,000 miners stormed across police roadblocks and threw rocks at police in the narrow Jiu Valley, on their way to the capital.

Forces from the special interior ministry used tear gas as the miners progressed through the valley, but failed to stop the marchers from reaching the town of Targa Jiu.

Fifteen people are reported to have needed hospital treatment following the clash.

The independent Romanian news agency Mediafax quoted Interior Minister Teodor Zaharia as saying the miners had been allowed to pass the last road block within the Jiu Valley, but that police had regrouped around Targu Jiu, and would use "all their strength" to prevent the miners from reaching Bucharest.

Miners defy police and continue to march to Bucharest

The miners have promised to continue unless the prime minister negotiates.

The miners' leader, Miron Cozma, has already rejected demands for them to go back to work, and correspondents say it looks unlikely that the march will be called off.

Spectre of past protest

Thousands are marching on Bucharest

The BBC Central Europe correspondent says the authorities are keen to bring an end to the protest, as they fear a repeat of the last miners' protest in Bucharest. That was in 1991, when they were used by neo-communist forces to overthrow a reformist government.

The government has said it will go ahead with plans to restructure Romania's loss-making industries, including mining. The austerity plan, prompted by the need for IMF funding, involves closing 140 coal mines.

The miners were forced to walk because the government refused to allow them to hire buses or trains.