Police are dealing with two security alerts in Londonderry less than than 48 hours after an explosion in the city centre.

The second alert on Southway in the Creggan area of the city follows a report of a vehicle being hijacked by four masked men at 13:45 GMT on Monday.

Police said one of the men was reported to be armed with a gun.

A security alert on Circular Road in Creggan is also ongoing.

It followed a report of a vehicle being hijacked by three masked men shortly before 11:30 GMT on Monday.

Police said the men reportedly "threw an object in the back of it" before abandoning the vehicle.

PSNI Supt Gordon McCalmont said: "We are in the process of implementing a public safety operation, establishing cordons and evacuating a number of homes.

"Sadly, within two hours today, we are dealing with a second security alert in the city, which means even more disruption for the local community," he said.

Supt McCalmont added: "I know this second security alert and the measures we are taking to keep people safe will cause significant inconvenience for the local community, but we have no choice."

A community centre in Central Drive has been made available to people who have been affected.

It follows continued disruption around the scene of Saturday's bomb outside Bishop Street Courthouse.

The PSNI said the attack may have been carried out by the New IRA, a dissident republican group.

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On Monday, police arrested a fifth man in connection with the bombing.

The 50-year-old man has also been arrested in connection with an armed robbery in the Meadowbank Avenue area of the city last Tuesday.

Courthouse closed

Four other men, two in their 20s and two others, one aged 32 and one aged 42, remain in police custody.

Police said a pizza delivery man had a gun held to his head as his vehicle was hijacked and then used in the bombing.

One CCTV clip posted on Twitter by police showed a group of young people walking past the vehicle shortly before the blast.

At the courthouse, scheduled jury trials have been put off until Tuesday.

Cases listed to be heard in the magistrate's courts are being held in Strabane, with some other hearings switching to Coleraine.

A police cordon has now been reduced but Bishop Street car park still remains closed.

In a Facebook post on Sunday, the PSNI said: "We are aware that a number of people are seeking the return of their vehicles - unfortunately this cannot be facilitated due to the continuing police operation.

"We would like to thank the community for their patience and support."

Driver 'threatened and intimidated'

PSNI Supt Gordon McCalmont told BBC Radio Foyle that the police were trying to get the city back to normal and show the attack had "little or no long-term impact".

He said the PSNI it was "lucky we are not talking about loss of life".

Supt McCalmont also said the pizza delivery driver "had to go through the drama of having a firearm put to his head".

"My thoughts are with that man today, He was threatened and intimidated.

"It would be fair to say he was asked not to raise the alarm."

What is the New IRA?

He added: "These groupings obviously want us to respond. We will be very balanced. This threat has always been in this city.

"My sense is that this is not because of Brexit."

Londonderry's city centre manager Jim Roddy told BBC Radio Foyle he was out walking when he got a call to say a car had been abandoned on Bishop Street.

"We could be looking at many deaths today," Mr Roddy said.

"There's been a lot of disruption but thankfully no one has been injured.

"Witnessing Saturday night was quite difficult as somebody who loves and tries to promote this city.

"Dozens of cars are still in the nearby car park. We'll be making representation to Transport NI to make sure no one gets tickets."