Three Egyptian police officers have been shot dead in an attack on a checkpoint in the Nile Delta city of Mansoura, security sources say.

Local security officials said gunmen on a motorcycle attacked the security forces in the Mansoura university checkpoint and fired randomly at the policemen.

No group has yet claimed responsibility for the deadly assault.

However, officials say it bore the hallmarks of militant groups who have stepped up attacks on soldiers and policemen since the army toppled former president, Mohamed Morsi, in July.

Most of their attacks have been carried out in the volatile Sinai region, although on occasions their carnage campaign has been extended into major cities.

The Sinai Peninsula has long been considered a safe haven for militants and criminal gangs who use the region as a base for terror activities.

Moreover, the ouster of Morsi, Egypt's first democratically-elected president, sparked mass protests which were met by a bloody crackdown from the army-backed interim government.

Egypt has plunged into an unrelenting string of violence since General Abdel Fattah al-Sisi, the head of the Egyptian army pushed aside Morsi and declared chief Justice of Egypt’s Supreme Constitutional Court, Adly Mansour, as the interim president.

Hundreds of protesters, mostly Morsi’s supporters, have been killed or wounded during the violence that has erupted since the removal of Morsi.