A dozen swans that were injured in an oil slick are all safely back on the river.

The Swan Sanctuary, based in Felix Lane, Shepperton, took in the stricken birds after they were caught up in an oil leak on the River Thames on July 14.

The Environment Agency was alerted after a member of the public spotted the slick between Westfield Landing and Charter Quay in Kingston.

Officers deployed absorbent booms and clean-up pads and an investigation into how the spill occurred has been launched.

Dot Beeson, of the Swan Sanctuary, said all the swans “had cleaned up nicely” and were now back among the 85 strong herd in Kingston.

The latest, a family of four, were returned on July 25.

Ms Beeson said: “We had a family of swans that we kept in for a few days extra. The mum and babies were ok but the dad was struggling so we kept him in for treatment.”

Ms Beeson said all swans were washed and given a stomach medicine after being caught up in the slick to prevent any further injury.

“This is happening every couple of weeks,” Ms Beeson said. “It is quite disgraceful that these spills are taking place. The swans become vulnerable to predators because they’re not waterproof after being caught up in oil but fortunately here it has been good news for these birds and they are all doing OK.”

Anyone who spots an environmental incident should call the Environment Agency on 0800 807060.