British police searching for a missing woman have found what they believe to be human remains, London police chief Cressida Dick says.

The grim find comes after the earlier arrest of a police officer on suspicion of kidnap and murder.

Sarah Everard, 33, was last seen on the night of March 3 as she walked home from a friend’s house in south London.

“This evening, detectives and search teams investigating Sarah’s disappearance have found very sadly what appears to be human remains,” Ms Dick, the head of London’s Metropolitan Police, said in a televised statement on Wednesday.

“The discovery was made in an area of woodland in Ashford in Kent. As you can imagine, at this early stage we are not able to confirm any identity, and indeed that may take us some considerable time.”

Earlier, police said the arrested officer, whose job was to guard diplomatic buildings, was in custody after being detained on Tuesday evening. The man in his 40s is also under suspicion of indecent exposure.

A woman in her 30s was also arrested at the same location on suspicion of assisting an offender.

The London force said the officer, who works for the Parliamentary and Diplomatic Protection Command, had not been on duty the night Everard disappeared.

Ms Dick said the news of the officer’s arrest had sent “waves of shock and anger” through the police force and the public.

Earlier, officers had been seen searching streets and nearby areas on her route home, which went near the large, grassy Clapham Common area in south London.

Officers were also searching locations in Kent, southeast of London, including a property in the seaside town of Deal and the area of woodland near Ashford.

-with AAP