ISTANBUL (AFP) - Violent anti-government protests that have engulfed Istanbul were triggered by plans to redevelop iconic Taksim Square in the heart of the city, a project that will involve razing some 600 trees in an adjoining park.

The plan includes building a replica of military barracks from the Ottoman Empire to house a cultural centre, but residents fear the area will in fact become a shopping district.

The Istanbul municipality, controlled by the Islamist-rooted Justice and Development Party (AKP) that has ruled Turkey since 2002, embarked on the ambitious project in November.

The plan aims to create a pedestrian zone around Taksim square, a traditional venue for rallies and protests as well as a popular tourist spot.

Work is under way to divert traffic leading to the busy central square from several directions into a tunnel, which officials say will beautify the tourist zone and keep the exhaust and noise of the city's traffic congestion underground.

With 15 million inhabitants, Istanbul is plagued with chronic traffic gridlock on the European side of the city.

But critics say the giant scheme, touted as also giving historic Taksim a facelift, will turn the square into yet another soulless, concrete commercial zone.

The project has drawn criticism from architects, urban planners and ecologists, who see it as another example of anarchic urbanisation conceived for real estate developers with no consideration for the environment.

The Turkish government and the city recently launched a series of giant projects in Istanbul, including a third bridge across the Bosphorus and a third airport, which will be built in the midst of one of the last "green" zones.

Violence erupted on Friday when protesters attempted to prevent workers from razing several trees in Gezi Park, which lies across from the square's centrepiece, the monument to Ataturk, founder of modern, secular Turkey.

Prime Minister Recep Tayyip Erdogan has said he will not abandon the plans despite the popular unrest, one of the biggest challenges his government has faced in its decade in power.

"We will rebuild the (Ottoman era military) barracks," Mr Erdogan said, though he added that it was unclear whether the new site will serve as a commercial centre.