CAIRO - Egypt's ultra-conservative Salafist Al-Nur Party has announced it will back the Muslim Brotherhood candidate Mohammed Mursi in a presidential election runoff against ex-premier Ahmed Shafiq.

"The High Committee of the Al-Nur Party supports Dr. Mohammed Mursi for president of the republic in the runoff," the party said on its official Twitter account.

The official results of Egypt's first presidential election since the 2011 uprising that overthrew Hosni Mubarak have yet to be made public. Egypt's electoral commission was expected to announce them later on Monday.

Unofficial results announced by the Brotherhood and multiple local media outlets showed Mursi set for a second-round run-off with Shafiq, after neither gained more than 50 percent of the vote in the first round.

But the head of the electoral commission, Hatem Bagato cautioned on Sunday night that "the results announced so far are only indications."

"The commission is in the process of examining appeals (about irregularities) and these appeals could change certain results," Bagato told private television station Al-Nahar.

The Al-Nur Party had backed moderate Islamist and ex-Brotherhood member Abdel Moneim Abul Fotouh in the presidential race after their candidate Hazem Abu Ismail was disqualified from standing.

Both Mursi and Shafiq have already been reaching out to their former rivals in a bid to assemble a coalition of support for the second round.

Two of Egypt's losing candidates, Amr Mussa and Abdel Moneim Abul Fotouh, on Monday declined to endorse either of the presumed front runners in a presidential election runoff.

Mussa and Abul Fotouh spoke at separate news conferences.

A "return to the old regime is unacceptable. So is exploiting religion in politics," Mussa told a press conference.

"Egyptians will only be comfortable with a civil state. A religious state is something very divisive," he warned.

Mussa had said before the presidential election, the first since Egypt's 2011 uprising, that he would retire from politics if his bid failed.

On Monday, however, he left the door open for talks with the other parties.

"I will not be consulting with anyone. If they want to consult with me, I will consider it," he said.

Abul Fotouh also refused to openly back a single candidate, but said a return to the old regime was unacceptable.

"We will announce our position when the results are announced," said Abul Fotouh.

"The most important thing is that people don't vote for a felool," Abul Fotouh said, using a common pejorative term for members of the old regime.