Erdogan's AKP challenges Turkey's Istanbul election results

Turkish President Recep Tayyip Erdogan's party appealed against election results in Istanbul this week, claiming there were "excessive" irregularities in this weekend's polling.

Sunday's municipal vote delivered a setback for Erdogan after preliminary tallies showed the Justice and Development Party (AKP) lost the capital and the economic hub Istanbul after a decade and a half in power.

Erdogan's AKP and coalition partner won more than 50 percent of the votes nationwide, but defeat in two key cities would be a blow after Turkey slipped into recession for the first time in a decade.

The AKP appeal with electoral authorities, who have two days to decide whether it has any merit, may signal further challenges from the ruling party to opposition victories in the two key cities.

"We have filed our objections with the electoral authorities in all 39 districts," AKP's Istanbul district chief Bayram Senocak told reporters. "We have identified irregularities and falsifications."

He said the party had found an "excessive" difference between votes cast at ballot stations for their candidate and the data sent to electoral authorities.

Istanbul, the largest city in the country, was a key prize for Erdogan and he had fielded his former premier and loyalist Binali Yildirim as candidate for mayor.

But Istanbul was a tight race and both Yildirim and the opposition CHP candidate Ekrem Imamoglu claimed victory in the early hours of Monday.

Electoral authorities on Monday announced Imamoglu was ahead by 28,000 votes with nearly all ballot boxes tallied, prompting AKP officials to challenge to the result.

Imamoglu had 48.79 percent of the votes while Yildirim had 48.52 percent, Anadolu state news agency reported on Tuesday, citing preliminary results.

Imamoglu on Tuesday travelled to Ankara to lay a wreath at the mausoleum of modern Turkey's founder Musfafa Kemal Ataturk in a highly symbolic gesture Erdogan often does himself soon after his election wins.

"Had the other party won, I would have said 'congratulations Mr Binali Yildirim', which I do not say because I am the one who won," Imamoglu told reporters.

"They are behaving like a kid who has been deprived of his toy."

AKP party spokesman Omer Celik on Monday had said they had found discrepancies between reports from polling stations and vote counts in both Ankara and Istanbul.

Erdogan, himself a former Istanbul mayor, had campaigned hard in the city. But the ruling party may have been stung by the economy with Turkey in recession for the first time since 2009 and inflation in double digits.