Anglian Water has agreed to pay £50,000 to an environmental charity after a blocked sewer sent black sludge flowing into a watercourse.

The Environment Agency agreed an enforced undertaking with the water company, which has donated the money to the Wildlife Trust Bedfordshire, Cambridgeshire and Northamptonshire.

The pollution happened at Highfield Farm, in Ravensden, near St Neots, with a blockage in the sewer from Yarlswood Immigration Centre sending sludge into a watercourse.

According to the Environment Agency, the blockage came about because of single-use shampoo sachets which the immigration centre provided for its residents. The resulting pollution raised ammonia levels in a watercourse.

There had been six blockages on the same stretch of sewer since 2011 when the sewer was transferred to Anglian Water, but it was not flagged on the company's mapping system until after the pollution incident in June 2015.

Practices for checking the sewer at the immigration centre have since changed.

The Environment Agency accepted the offer by the water company to donate to the charity and put right any damage that the pollution caused.

The money will benefit environmental projects in the Nene Valley and Ouse Valley Living Landscape areas.

Anglian Water also paid the Environment Agency's legal costs amounting to £3,451.

Chris Tate, Environment Agency team leader, said: "Enforcement undertakings allow those who commit offences to restore the environment and to take steps to prevent a recurrence.

"When appropriate, they allow a quicker resolution than a prosecution and help offenders who are prepared to take responsibility for their actions to put things right voluntarily working with their local communities."

An Anglian Water spokesman said: "Ultimately our goal is no pollution and we have a significant programme of activity and investment to help achieve this and understand the causes of any that do occur.

"We regret any that do happen, no matter how small, and support enforcement undertakings as a sensible, proportionate response that benefits local communities and the environment.

""The blockage caused a manhole to overflow into a nearby watercourse.

"As soon as our teams were made aware of the incident, we responded quickly to clear the area and there was no evidence of any impact to fish or insects."