The number of substantiated complaints against police in Lambeth tripled last year.

Some 15 investigations in to 448 complaints made against police in 2008-9 found the complaint was justified, a Freedom of Information request showed.

In 2007-8 just five complaints were substantiated.

Lambeth’s borough commander Chief Superintendent Nick Ephgrave, said the police took all complaints “very seriously”.

But he said it was also important to consider the number of complaints were still very low, considering Lambeth police had more than 1,000 officers constantly interacting with the public.

Complaints made included allegations of sexual assault, corruption, discriminatory behaviour and assault, and rose in number from the previous year.

All substantiated complaints were those dealt with by internal police investigations. None of the 166 complaints received by police watchdog the Independent Police Complaints Commission (IPCC) were found to be justified.

In 2008-2009, Lambeth police paid out a total of £22,350 in compensation to six people who took, or threatened to take civil action against them.

The amount paid out was significantly less than the £76,431 and £60,000 paid out in 2006-7 and 2007-8 respectively.

Chief Supt Ephgrave said he would always encourage anyone who felt they had been treated badly by police to make a complaint.

A police spokesman said: “The MPS treats each occasion where an allegation is received seriously and will fully investigate that incident to determine whether a criminal offence and/or breach of conduct for police officers has taken place.

“The MPS expects its staff to behave professionally, ethically and with the utmost of integrity at all times. Any instance where the conduct of our staff brings the MPS into disrepute is taken extremely seriously in line with MPS policy."

No officer lost their job as a result of complaints made against them between April 2006 and March 31, 2009.