Ankara (AFP) - Turkish President Recep Tayyip Erdogan is on Wednesday set to unveil his new presidential palace on the outskirts of Ankara, denounced by ecologists as an environmental blight and by the opposition as new evidence of his autocratic tendencies.

Erdogan will host his first official event at the new palace, a reception marking Turkey's annual republic day which celebrates the foundation of modern Turkey in 1923 out of the ruins of the Ottoman Empire.

The complex, located in the Bestepe (Five Hills) area, has become known as the Ak Saray -- the White Palace.

An immense project built at a reported cost of $350 million, it has an area of 200,000 square metres, 1,000 rooms and architecture that is supposed to marry modernism and the traditions of the mediaeval Seljuk dynasty.

It will become the new home of the Turkish presidency, marking an historic break with the Cankaya presidential palace in downtown Ankara.

The Cankaya has been the seat of the Turkish president ever since the modern republic's founder Mustafa Kemal Ataturk became president and for many has been a symbol of Turkey's modern history as a progressive secular state.

From Ataturk to Erdogan, it has been the home of 12 Turkish presidents.

The move to the new palace is a vivid symbol of what Erdogan touts as his drive towards a "new Turkey".

But for the opposition, the new palace marks another betrayal by Erdogan of Turkey's secular heritage bequeathed by Ataturk who based the republic on a strict separation of religion and state.

- Opposition boycotts reception -

The opposition accuses Erdogan, who became president in August after over a decade as prime minister, of imposing a gradual Islamisation and riding roughshod over Turkey's democracy.

For them, Erdogan has rubbed more salt into the wound by opening the palace on republic day, the dearest of all Turkish holidays for secularists.

The three opposition parties represented have called for a boycott of the reception.

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"If you don't go, you won't tarnish yourself," said the head of the main opposition Republican People's Party (CHP) Kemal Kilicdaroglu.

The Bestepe complex had initially been envisaged for the Turkish prime minister but in the end Prime Minister Ahmet Davutoglu and his staff will move into the Cankaya.

The name of the palace, Ak Saray, is also a play on the name of the ruling Justice and Development Party (AKP) which is known to its followers as the AK Party.

The post of president has been a largely ceremonial role in recent years. But Erdogan has vowed to wield real power, something he has clearly done in his first weeks in office.

The new complex is also controversial among environmental activists because hundreds of trees were cut down to make way for it, even though it was one of the best preserved green spaces in the city.

Furthermore, the palace has been built on land where Ataturk created a forest farm that was then donated to the state. Erdogan in March defied a court order halting the construction.

According to Turkish media, the design of one of the offices is based on the White House's oval office, and has no electrical safeguards against wiretapping.