Brazil's President Dilma Rousseff has asked the Supreme Court to block impeachment proceedings against her - in a final attempt to stop the process hours before a crucial Senate vote.

Rousseff's lawyers alleged bias and irregularities. Similar attempts have been rejected by the court.

Rousseff could be suspended for up to 180 days if the senators vote for a full trial on Wednesday.

Earlier, her supporters set up burning barricades and blocked roads.

The roadblocks caused widespread disruption across all Brazilian states.

Waldir Maranhao, acting speaker of the lower house of Congress, caused fresh surprise on Tuesday when, less than 24 hours after suspending a vote in the chamber that had allowed the impeachment process to go ahead, he reversed his decision.

Previously he had argued that the 17 April vote had breached Congress rules. Members had voted overwhelmingly in favour of the impeachment process going ahead.

The president is accused of illegally manipulating finances to hide a growing public deficit ahead of her re-election in 2014, which she denies.

(BBC)