Image caption Michael Moore said: "We're going to do this together"

Thousands of people have joined protests in the US state of Wisconsin against proposals that will limit the power of trade unions.

In the city of Madison, filmmaker Michael Moore told them: "We're going to do this together. Don't give up."

Republican Governor Scott Walker has proposed stripping collective bargaining rights as part of a budget-cutting bill.

State Democrats fled to Illinois to prevent any legal vote on the bill.

Their absence deprives the state legislature of a quorum.

Senate Republicans voted on Thursday to hold the missing Democrats in contempt and force police to bring them back to the capitol.

Governor Walker on Friday sent out redundancy warning notices to unions representing state workers following the failure to pass the bill.

He says the measures are needed to tackle a $3.6bn budget gap over the next two years.

Republican praise

Mr Moore said: "Madison is only the beginning. The rich have overplayed their hand."

Senator Chris Larson also urged protesters to remain strong.

"We've been here for the last 16 days [and] we'll continue to be here until worker's rights are removed as the target in this budget repair bill by our governor," he said.

Mr Walker has said his proposal would balance the state's budget without raising taxes or cutting jobs.

The bill, which must pass in both chambers of the legislature, is part of a broader economic policy that aims to get the deficit under control in part by restricting public employees' collective bargaining rights and by requiring them to contribute more to their pensions and healthcare.

State unions have said they will agree to Mr Walker's proposed changes to their benefits - which would amount to an 8% pay cut - as long as they retain collective bargaining rights.

Critics of Mr Walker's proposal say it is intended to weaken the power of the unions, which tend to back the Democrats in elections.

Republicans, who in November took control of the US House of Representatives and state capitols across the country, have praised Mr Walker's bid to balance the budget without raising taxes.