Riot police used tear gas and pressurized water to disperse people staging a sit-in to prevent the uprooting of trees at a park in Istanbul, Turkey.

Several protesters were injured when a wall they climbed collapsed during a police chase and a prominent journalist was taken to hospital after being hit in the head by a tear gas canister, according to reports.

Police moved in to disperse the crowd on the fourth day of the protest against a government plan to revamp Istanbul's main square, Taksim. Officers then clashed with demonstrators in surrounding areas.

The protesters are demanding that the square's park, Gezi, be protected.

Protesters in Gezi Park were seen holding up a large poster with a caricature depicting Turkish prime minister Recap Tayyip Erdogan as an Ottoman sultan with a caption that read: "The people won't yield to you."

Erdogan dismissed the protesters' demands for the park's protection, saying the government would go ahead with renovation plans "no matter what they do".

The forestry minister said more trees would be planted than those uprooted at Gezi and has defended the government's environmental record.

The raid was the latest in a series of crackdowns on protests. Human rights activists frequently accuse Turkish police of using inordinate force to break up protests and of excessively using tear gas and pepper spray against protesters.

On Friday, demonstrators affected by the gas sought shelter at a luxury hotel at Taksim. Police removed tents and demonstrators' other belongings and mounted barricades around the park.