Egypt's state news agency, MENA, reported that the results would be released later on Monday, although a senior member of the national electoral commission said no date for their release had been set.

Preliminary results released on Sunday, though, indicate more than 60 percent of those who voted on December 15 and 22, backed the charter. This was welcomed by President Muhammad Morsi and his Islamist Muslim Brotherhood, whose members dominate the legislative assembly that wrote the draft.

Shortly after the preliminary results were announced, President Morsi called on the opposition to "respect the will of the people."

For the president and his allies though, the downside of the preliminary results was that turnout was extremely low, at just over 30 percent.

The opposition vowed to keep up the fight against the draft constitution, which they believe would weaken the state of human rights in the country.

The opposition coalition National Salvation Front complained of voting “fraud and violations” and said it would launch a legal challenge.

"We are asking the [electoral] commission to investigate the irregularities before announcing official results," a Front member, Amr Hamzawy, told a press conference in Cairo on Sunday.

Germany quickly backed the call for an investigation.

"The new constitution can only meet with acceptance if the process of its adoption is beyond reproach," German Foreign Minister Guido Westerwelle said.

"Not the power of the street, but the spirit of compromise and tolerance should determine the direction that the new Egypt embarks upon," Westerwelle added.

pfd/jlw (AFP, dpa)