Egypt's disputed constitution has won national backing, early results released by the Muslim Brotherhood say.

Votes are counted in Egypt's referendum on the adoption of a new constitution (Reuters)

Preliminary results released on the Muslim Brotherhood's website said that a majority of 70 per cent voted in favour of Egypt's new constitution in the second and final round of voting.

The second vote, which covered around half of Egypt's population, followed the first round on 15 December. That vote secured a 56 per cent majority in favour of the constitution, meaning overall the reform is expected to have received a 64 per cent vote in favour.

Egypt's constitutional reform has sparked waves of violent clashes between those who oppose the document and the way it has been drafted, and sympathisers with Egyptian president Mohamed Mursi (pictured, below right) and the country's dominant Muslim Brotherhood movement.

It was expected that the second vote would be in favour of the constitution as it largely took place in the country's rural areas which are traditionally dominated by Islamist sympathisers.

At 30 per cent, turnout was comparitively low, with 16.6 million eligible voters taking part.

Mohamed Mursi holding the draft constitution (Reuters)

Voting irregularities?

Opponents say the constitution, which was drawn up in private, favours Mursi's Islamist allies to the detriment of groups such as the country's Christian community and women. Supporters say the constitution is vital to restoring stability to the country following the Arab Spring and the ousting of former leader Hosni Mubarak.

Allegations have been made of voting irregularities, such as illegal campaigning in favour of the constitution outside polling station, and the recording of at least one dead person as having voted.

The body monitoring the the elections said it had found no serious cases of wrongdoing.

However, the National Salvation Front, the main opposition party, said it would continue to challenge the results.

"We are questioning the results," Khaled Dawoud, the front's spokesman, told the Associated Press. "We don't think the results reflect the true desires of the Egyptian people." He said the opposition will be filing official complaints.

The new constitution will come into effect once official results are announced, expected Monday. When they are, Morsi is expected to call for the election of parliament's lower chamber, the more powerful of the legislature's two houses, no more than two months later.

The National Salvation Front, said it will now focus on rallying for elections for the lower house of parliament. However, it remains to be seen whether opposition will see further clashes on the streets of Egypt.