Turkey’s opposition alliance has accused state media of “deceiving” the public with early results of Sunday’s election, underscoring the intense battle between president Recep Tayyip Erdoğan and rival Kemal Kılıçdaroğlu.

Erdoğan has secured about 51 per cent of the vote, compared with just 43 per cent for Kılıçdaroğlu, according to figures collated by the state Anadolu news agency, based on the count from 70 per cent of ballot boxes. By contrast, the Anka news agency put Kılıçdaroğlu at 46 per cent and Erdoğan on 48 per cent, based on 65 per cent of ballot boxes.

Kılıçdaroğlu’s allies on Sunday objected to data provided by Anadolu, arguing that the calculations had excluded areas where the opposition had performed well and claimed that Erdoğan’s Justice and Development party (AKP) was slowing down the counting process by raising objections in opposition strongholds.

“My advice is ignore Anadolu agency numbers because they are trying to deceive you,” Ekrem İmamoğlu, the Istanbul mayor who is one of the top leaders in the “table of six” coalition, said on Sunday.

İmamoğlu described Anadolu’s reputation as “below zero”, citing past examples where the agency had given an outsized lead to government candidates in the early stages of vote counting.

Mansur Yavaş, Ankara’s mayor and another leading opposition official, said each main candidate had around 47 per cent of the vote, but that many ballots were yet to be counted in major cities.

AKP spokesman Ömer Çelik defended Anadolu, saying that it remained the main source for election reporting and that the “attacks” by Kılıçdaroğlu’s CHP party amounted to “propaganda”. He said it was too early to declare a winner, and called for patience.

“Whatever the results of the election, we have a tradition of respecting the results. The tradition of not respecting the results with coups, memorandums and the tutelage of the judiciary is with you,” Çelik said of the CHP.

In a potential upset to both main candidates, Sinan Oğan, a presidential hopeful who broke from the ultranationalist Nationalist Movement party, has gained around 5 per cent of the votes, according to both Anka and Anadolu figures. His vote share is significant because it could prevent the two main candidates from passing the 50 per cent required to avoid a run-off election in two weeks’ time.

Polling centres had been busy across Turkey after more than 60mn people registered to vote in presidential and parliamentary elections that offer two widely divergent paths for Turkey.

Erdoğan, who first carried the AKP to power in 2002, faced his toughest campaign as he sparred with Kılıçdaroğlu. The results will carry global resonance because Turkey, a member of Nato, has played an increasingly important role on the international stage in recent years.

Kılıçdaroğlu has vowed to revive Turkey’s ailing economy, bring the country closer to the west’s orbit and restore crucial institutions that have been undermined during Erdoğan’s long tenure, first as prime minister and now as president.

The 74-year-old opposition leader has regularly campaigned with other popular politicians who are part of the “table of six” coalition, including İmamoğlu and Yavaş.

Polls published in the lead-up to Sunday’s election gave Kılıçdaroğlu an edge over his 69-year-old opponent, with Erdoğan’s handling of the country’s $900bn economy having severely dented his support. But analysts and even senior opposition officials warned against underestimating Erdoğan, who has dominated Turkish politics in a way no other person has since Mustafa Kemal Atatürk founded the republic a century ago.

Erdoğan, whose final campaign stop on Saturday was attending evening prayers at Hagia Sophia mosque in Istanbul, remains popular with conservative, pious voters in Turkey’s Anatolian heartland.

At fiery campaign rallies, Erdoğan has framed himself as the only politician who can secure a prosperous future for Turkey and defend family values. On Saturday, he also accused Kılıçdaroğlu of working with US president Joe Biden to defeat him, without presenting evidence.

Kılıçdaroğlu, meanwhile, called on voters to “change Turkey’s destiny” by voting for his opposition alliance.

There was also a significant police presence on Sunday with motorcycles zipping up and down the streets of Istanbul and heavily armoured trucks and heavy crowd-control vehicles patrolling in the heart of Ankara, the capital city.

Süleyman Soylu, interior minister, said 600,000 security guards, police, gendarmerie, coast guard and security guards were on duty in response to “the district election boards’ call”.

Turks also on Sunday voted in parliamentary elections, which could shake up the balance of power. An alliance between Erdoğan’s AKP and the ultranationalist Nationalist Movement party holds a majority in the legislative branch.