Turkish President Recep Tayyip Erdogan is planning to expand his controversial, grandiose presidential palace with a 250-room residential building, Ankara's top architect confirmed on Thursday (13 November).

The additional residency complex will be built adjacent to the palace, confirmed Tezcan Karakus Candan, the chairman of the Turkish Chamber of Architects in Ankara.

"The residence where the president will live is set to be around 7,000 square metres, according to our calculations. It is about 4,000 square metres in surface. If each room is 20 metres, then it means he is building himself a residence with 250 rooms," said Candan.

Candan has questioned the legality of Erdogan's "unlicensed palace."

Metin Kiratli, the deputy chief of the presidential administration, reacted to the criticism, telling the official Anatolia news agency: "These claims have no basis. We have a licence that granted us a construction permit as well as another licence for the use of the building. Therefore there are no administrative problems."

The senior presidential official did not comment on the alleged residential building.

The Presidential Palace, dubbed the 'Aksaray (White Palace)' has 1,000 rooms. Its architecture has been inspired from Turkey's Ottoman and Seljuk heritage.

Critics condemn Erdogan's autocratic tendencies

Finance Minister Mehmet Simsek said last week that the White Palace has cost Turkey a whopping £392 million (1.37 billion Turkish lira), which is double the original estimated cost.

The vast palace in the outskirts of Ankara has faced heavy criticism, with the opposition comparing it to the likes of the Romanian dictator Nicolae Ceausescu's palace.

"1,000 rooms were not enough," said opposition Cumhuriyet daily.

Environmentalists have also criticized the palace, which is built on an area that is considered to be one of Ankara's last green areas, claiming it was constructed in defiance of a court ruling against the building of the palace.

Erdogan's oldest allies, Deputy Prime Minister Bulent Arinc, has added his support to the criticism saying: "This was not a small sum of money."

The Presidential Palace will welcome its first foreign guest next week when Pope Francis visits Ankara for his three-day Turkey visit starting 28 November.

The Turkish Chamber of Architects in Ankara are urging the Pope "not to legitimise the illegal building," and have written a special letter to him addressing their concerns.