ISTANBUL (AFP) - Turkish President Recep Tayyip Erdogan on Friday inaugurated a mosque inside his controversial presidential palace and opened it to public in an apparent bid to deflect criticism over his lavish spending on the complex.

Erdogan's 1,150-room palace, which was built at a cost of around €490 million (S$730 million) in the Bestepe district of Ankara, has been condemned by critics as an absurd extravagance that shows he is slipping further towards authoritarian rule.

Erdogan, who in recent weeks has appeared to respond to such criticism, dedicated the mosque to the people, naming it "Bestepe People's Mosque" in the opening ceremony which coincided the Islamic fasting month of Ramadan.

The mosque spans some 5,377 sq m on the grounds of the presidential complex and includes a prayer hall that can accomodate up to 3,000 worshippers.

With four 60m-high minarets, the mosque draws its architectural inspiration from Turkey's Ottoman and Seljuk heritage, Erdogan said.

"I am praying to God that the prayers recited in this mosque will be accepted by Him," Erdogan said.

Erdogan, who rarely tweets, later wrote on Twitter, signing off with his initials RTE: "I hope that Bestepe People's Mosque fosters our unity, solidarity and brotherhood."

The Islamic-rooted Justice and Development Party (AKP), co-founded by Erdogan, lost its overall majority in June 7 parliamentary elections, in a blow to Erdogan's ambitions to change the constitution to increase his powers.

The palace has been the subject of a sometimes farcical dispute in the run-up to the elections between Erdogan and the main opposition leader Kemal Kilicdaroglu, who accused him of having golden toilet seats there.

Erdogan denied the claims, invited Kilicdaroglu to visit the palace to find the rumoured toilets and filed a lawsuit against him, seeking compensation for slander.

Erdogan defends the palace by saying that it belongs to the people and is a worthy symbol of the new Turkey he is trying to build.

He once justified the construction by saying that the presence of cockroaches in his old offices when he was prime minister were the reason why he needed a vast new presidential palace.

Turkish officials recently launched a virtual tour of the palace and said that some parts of it such as a congress hall and one of Turkey's biggest libraries with over five million books, which is under construction, will also be open to the public.