Homes in Derry have been evacuated after a suspicious object was found during searches.

The object was discovered in a house in the Creggan Heights area of Derry amid searches for bomb-making material, the PSNI confirmed.

"As today's public safety operation progresses our efforts are now focused in the area of Creggan Heights following the discovery of a suspicious object. We will continue to keep the community updated," said the PSNI.

Residents were initally prevented from entering the residential street as a police cordon was put in place across Rathmore Crescent and the main road leading up to the Creggan Heights area.

A number of uniformed PSNI officers could be seen around the area, and entering and exiting a house in Creggan Heights where the device is believed to have been found.

The PSNI have said several missiles had been thrown at officers in the vicinity.

The PSNI confirmed officers would evacuate homes at around 4:45pm.

"Following the discovery of a suspicious object in the area of Creggan Heights, and to ensure the safety of local residents, the decision has been taken to evacuate homes," a statement said.

PSNI Superintendent Gordon McCalmont said earlier on Monday that dozens of officers would engage in a search for bomb-making material on the Creggan estate after a dissident republican mortar bomb was recovered in the Irish border town of Strabane on Saturday.

Dissident Republican group New IRA were blamed after a passer-by found the explosive device on a wall on Saturday morning. It had been sitting there for hours, close to a family home, police said.

It was the seventh incident of its kind this year and senior officers are alarmed by the threat posed by anti-peace process gunmen.