Violence erupted in Rio de Janeiro's business district on Tuesday as police clashed with striking schoolteachers.

Teachers pressing for better pay had gathered in front of City Hall, where a vote on Mayor Eduardo Paes's (pictured) salary proposal was expected.

The strikers oppose the mayor's proposal, which they say doesn't go far enough to addressing their demands.

Chaos broke out in the late afternoon when police officers set off deafening percussion grenades and fired rubber bullets at demonstrators.

Anarchist group Black Bloc also joined the protest, shattering glass at banks, bus stops and traffic lights and burning rubbish to block streets.

In addition to tear gas, police used stun guns and pepper spray. They arrested 17 people, claiming that none of the detainees were teachers.

Negotiations between the city and the teachers' unions have been acrimonious.

Teachers opposed to the mayor's pay proposal have invaded City Hall trying to disrupt proceedings and police have repeatedly sprayed strikers with clouds of tear gas, rubber bullets and percussion grenades.

Public primary and pre-school teachers have been on strike for 46 days because their union says the proposed wage increase will only benefit 7 per cent of teachers.

The planned increase would only apply to teachers who work 40 hours a week, which is a small minority, said demonstrating teacher Daniel Raposo.

He said most teachers made just 28 reals (£7) an hour.

As the percussion grenades exploded outside, dozens of people took shelter in the plush Odeon cinema, which is hosting events for the Rio Film Festival.

On Monday night a skirmish between riot police and protesters sent hundreds of festival-goers who had just emerged from the evening's gala screening racing back into the cinema to avoid the street skirmishes.

Rio police have been criticised for violent responses to demonstrations that have swept the city since June, when small protests against a fare rise in Sao Paulo snowballed into a nationwide movement.

The head of the police was ousted, but allegations of brutality against demonstrators have persisted under his successor.