Anti-government protests against a building project are continuing to rock the Turkish city of Istanbul despite a police crackdown.

Security forces again used tear gas and water cannons to quell the protesters.

Earlier in the day, crowds tried to march to Taksim Square, but were foiled by security forces.

Angry demonstrators hurled stones at police, raising tension.

Other Turkish neighbourhoods also witnessed unrest. In the capital city of Ankara, protesters tried to march on the country's parliament.

Scores of people have been injured in the clashes, and many have been detained.

"There are 40,000 people crossing the bridge between Asia and Europe today. All the public transport is on lockdown. About half past one the entire city started to reverberate. People were banging on pots, pans, blowing whistles," an Istanbul inhabitant named Lily told the BBC World Service.

Local media reports say police forces have been coming down heavily on the residents and protesters alike, without making any distinction.

Two helicopters have also been deployed and dozens of ambulances have been spotted carrying injured people to hospitals.

Kemal Kilicdaroglu, the main opposition leader, has urged Prime Minister Recep Tayyip Erdogan to withdraw the police forces from the protest area.

"Don't confront the people with police. Withdraw the police immediately from the Taksim Gezi [Park] area. People are defending their city. That's why they are resisting. Show that you are the prime minister and make a public statement that you will respect the court's ruling. This is your duty," he said.

Pro-environment campaigners launched the protests as a peaceful rally against Erdogan's latest move to implement a controversial development project at Gezi Park in Istanbul. The demonstrations turned violent after skirmishes erupted.

A protester prepares to throw a stone at riot police during an anti-government protest in central IstanbulReuters
A protester throws a stone at riot police during an anti-government protest in central IstanbulReuters
Protesters clash with riot police during an anti-government protest in central IstanbulReuters
Riot police use a water canon to restrain a protester during an anti-government protest at Taksim Square in central IstanbulReuters
A protester with a Guy Fawkes mask clashes with riot police during an anti-government protest in central IstanbulReuters
Riot police use tear gas to disperse the crowd during an anti-government protest at Taksim Square in central IstanbulReuters
Riot police use tear gas to disperse the crowd during an anti-government protest at Taksim Square in central IstanbulReuters