Turkey’s election body said the country will head for run-off as the incumbent President Recep Tayyip Erdogan has slightly fallen short of garnering the 50% of votes necessary to maintain his seat.

With 99% of ballot boxes opened, High Election Board head Ahmet Yener said on Monday Erdogan's main rival Kemal Kilicdaroglu received 44.96% of the votes.

There are now speculation surrounded who the third presidential candidate, Sinan Ogan, would throw his weight behind in the second round. Ogan, who has been described by analysts as "kingmaker", took some 5.2% of the votes.

In an interview with German news site Der Spiegel, Ogan said he would only support the opposition Nation’s Alliance if the “(The pro-Kurdish) HDP is excluded from the political system.”

Erdogan said in a speech to his cheering supporters at the headquarters of his ruling AK Party in the capital Ankara overnight that, "The winner has undoubtedly been our country."

Pro-government media cheered the results, with Yeni Safak newspaper proclaiming "The people won", referring to Erdogan's People's Alliance that appeared to have won a majority in parliament, potentially giving him a crucial edge in the presidential runoff.

In the early hours of Monday, Kilicdaroglu also vowed to win the run-off election, which will take place on May 28.

Kilicdaroglu, who heads a six-party alliance, has accused Erdogan's party of interfering with the counting and reporting of results.

The results were surprising after late pre-election polls had put Kilicdaroglu slightly ahead.

People in Turkey cast their ballots on Sunday, and reported election turnout was a very high 88.8%.

The presidential election poses the biggest challenge to 69-year-old Erdogan, amid an economic downturn and the impact of the devastating February 6 earthquake.

Kilicdaroglu has promised to fix Turkey’s faltering economy and restore democratic institutions compromised under Erdogan’s rule.

Erdogan, on the other hand, has been extolling the virtues of his long rule, campaigning on a platform of stability, independent foreign policy, and continuing to bolster Turkey’s defense industry.

Recently, he raised the wages of government workers by 45 percent and lowered the retirement age.

His AK (Justice and Development) Party has been in power since November 2002, and he has ruled Turkey since 2003.