Istanbul's deposed mayor Ekrem Imamoglu said Wednesday that no one believed the "lies" used to overturn his recent election and called on voters to "correct this great shame" in next month's re-run.

"Nobody believes their claims," Imamoglu said at a meeting in Istanbul to launch his re-election campaign.

He accused President Recep Tayyip Erdogan's ruling party of peddling "lies" and "excuses" to overturn his narrow victory in the mayoral election in March.

"When I look at their facial expressions, I see that they themselves do not believe them either," Imamoglu said.

The election board earlier this month accepted the ruling party's allegations of "irregularities" and called a re-run of the vote for June 23.

Imamoglu's victory for the opposition of the Republican People's Party (CHP) was the first time Erdogan's Islamic-conservative party and its predecessors had lost control of the metropolis in 25 years.

- Patronage resources -

Analysts say the government is reluctant to cede control of Turkey's biggest city, which provides its mayor with significant resources for patronage as well as a high-profile platform.

"We will show the whole of Turkey on June 23 that there is no way out other than democracy and the ballot box," Imamoglu said.

Imamoglu has focussed on reversing extravagant spending in the city's finances which he said he discovered during his brief 18-day stint as mayor / © AFP

"Come and let's correct this great shame and unfairness all together."

Imamoglu said his campaign would focus on reversing extravagant spending in the city's finances which he said he discovered during his brief 18-day stint as mayor.

"The resources of Istanbul municipality are being plundered... Istanbul municipality is not the property of a handful of people," he said.

The opposition candidate also accused the ruling party of copying his proposals, including reduced water bills and discounted student transport, saying it was like a schoolboy copying his homework.

But he sought to maintain a positive message, in line with his efforts to bring unity to Turkey's fiercely partisan politics.

"We will embrace everyone... Everyone is a patriot... You will see at the end of this process we will love each other more."

The election board released its full explanation for cancelling the results of the first election late Wednesday, citing a spate of irregularities including in the appointment of polling station heads which under law must be civil servants.

In a 250-page document, the board said the number of "suspicious votes" were more than 300,000.

Imamoglu won a tight 13,000-vote lead over his rival Binali Yildirim of the ruling party, a former prime minister.

The top election body ruled seven against four in favour of a re-run.

It did not annul the votes for the city council that were cast at the same time, and where the majority of seats went to Erdogan's ruling Justice and Development Party.