Some 2700 pro-independence protestors turned out for a seventh night in a row in Barcelona on Sunday, to express their anger over the recent jailing of nine Catalan separatists.

One group of protesters blocked a main road in central Barcelona, near the Spanish government headquarters. They threw sacks of trash at parked police cars, but there was no sign of the recent violence that has rocked the city since Monday.

Spain's interior ministry says 288 police officers and several hundred protesters have been injured in the clashes, which culminated on Friday in the biggest mass protest yet- with half a million people joining a general strike which brought the city to a standstill.

A police officer and a protester are in critical condition, according to Barcelona's Mayor Ada Colau, who has pleaded for the violence to stop.

Protesters are demanding the release of the nine jailed separatists, who were convicted over their role in a failed referendum for independence in October 2017.

The demand for independence is deeply divisive in Catalonia, which is Spain's richest region. Pro-unionists mounted their own protests on Sunday, calling for a return to law and order, and accusing the Spanish government of not doing enough to quell the violence.

Spain's acting Socialist Prime Minister Pedro Sanchez rejected calls to hold talks with Catalonian leaders aimed at resolving the crisis, and criticized the region's president Quim Torra for failing to categorically condemn the violence.

Meanwhile Barcelona authorities are scrambling to repair the damage caused by the protests, amid fears the region's tourist industry has taken a significant hit.

Businesses have warned the cost of the damage could run to several million euros, while the transport industry alone says losses amount to 100 million euros since the protests broke out last Monday.

There are also concerns "Tsunami Democratic" - an anonymous online pro-independence activist group organizing spontaneous protests- is determined to stoke the violence further.