For the first time since the Serbian opposition began daily anti-government demonstrations nine days ago, police used force on Wednesday to prevent protesters from marching on Yugoslav President Slobodan Milosevic's residence in Belgrade.

The violence came on the eve of a crucial meeting of rival opposition leaders that's designed to bridge their differences.

The Alliance for Change - the umbrella-group of Serbian opposition parties that has been co-ordinating daily protests for over a week - says over 60 of its supporters were injured when riot police charged into a crowd of around 20,000 demonstrators in the centre of Belgrade.

The police said five officers had been hurt by demonstrators who were described as "known criminals and hooligans".

But one of the Alliance's leaders, Zoran Djindjic, denied the protesters had any plans to provoke violence.

"We do not want to fight Milosevic's servants," he said. "We want him, not the police. He can keep on sending them here, but they are not our enemies."

Stakes raised

The police action is expected to raise the stakes in the confrontation between the opposition Alliance and the authorities.

A demonstrator prepares a barricade in Belgrade

During a previous bout of demonstrations three years ago, the use of force by the police created a backlash, and it stiffened the protesters' resolve.

After three months of unprecedented daily protests across Serbia, President Milosevic was forced to concede the opposition's electoral victories in 14 municipalities.

New ideas

In 1986, the opposition parties were united in what was known as the Zajedno alliance.

This time, though, there are serious divisions among the parties and one - the conservative Serbian Renewal Movement - has so far been boycotting the demonstrations.

But leaders of the Serbian Renewal Movement are today meeting their colleagues from the Alliance for Change in a bid to overcome their differences.

They are discussing ideas for electoral reform - such as the introduction of proportional representation.

No concessions

If the rival opposition groups can reach agreement on a set of proposals, it would increase pressure on President Milosevic's administration.

Opposition parties discussed whether they could work together

But the government, led by Preisdent Milosevic's Socialists, doesn't appear to be in the mood for making concessions.

That could prompt the leader of the Serbian Renewal Movement, Vuk Draskovic, to reconsider his boycott of the demonstrations.

Until now he's opposed the protests, arguing instead for early elections.

But the Alliance for Change, and its best-known leader, Zoran Djindjic, have been adamant that conditions for free and fair elections do not exist in Serbia while the Milosevic administration remains in power.

That's why their campaign of protests has been aimed at installing a technocratic caretaker which would create acceptable conditions for holding proper elections.

It's not yet clear if the Alliance and the Renewal Movement can agree on a common set of demands.

If they did, it would certainly make life more difficult for the authorities.

For the moment, all these moves appear to be part of what could become a long drawn-out political process; and the meeting of rival opposition leaders is just the first tentative step towards trying to rebuild the unity that was lost over two years ago.