Riot police patrol Helen's Bay beach party

Riot police were on patrol on a beach in north Down on Saturday following reports of fighting.

It is understood thousands of people came to the beach for a party which had been promoted through social media sites.

The Environment Agency staff said they picked up five tonnes of litter on the beach at Helen's Bay on Sunday.

Mert Thompson, warden at Crawfordsburn Country Park, said there has been an "incredible amount of litter".

He said staff had been working from 06:00 BST on Sunday to clear the area.

"The litter problem was exceptionally bad, there were a couple of fields there at the front of Crawfordsburn and Helen's Bay where we could barely see the grass for litter," he added.

"I've never seen anything like it - it was piled thick in places."

Local resident Laura Graham helped to clean the area.

"I don't think anybody understands any longer that you can't just leave stuff lying, it wrecks it for everybody else.

Mayor of Bangor James McKerrow said the alcohol ban needed to be enforced more rigorously.

"We are not against people coming here - look at the families and look at people enjoying themselves," he said.

"It is a place to be enjoyed but we want to curb the excesses."