A major police investigation is under way in Keighley into allegations of sex offences spanning three decades.

Detectives have revealed that an inquiry is ongoing into reports of “historic” sexual offences against a woman, now in her 40s.

The allegations cover a period from the 1970s to the last decade.

Four people – a 67-year-old woman and three men, aged 66, 67 and 70, all from the Bradford area – have been arrested as part of the investigation.

They were released on police bail pending further inquiries.

Officers and forensic teams have been carrying out a fingertip search of a house in Keighley in connection with the inquiry.

A neighbour said: “There has been intense police activity over several days.

“Forensics have been searching the house and they were there all one night.

“There was a policeman stood outside but they wouldn’t tell anyone what was going on.

“Everybody has been talking about it.”

Police say the investigation began in 2012, after the complainant came forward.

Detective Inspector Vanessa Smith, of the Bradford District Safeguarding Unit, said: “West Yorkshire Police are investigating a report of historic sex offences against an individual victim, which are alleged to have occurred at an address in Keighley.

“Three men and a woman were arrested on suspicion of serious sexual offences and have now been released on bail.

“Inquiries are ongoing.”

News of the investigation has come to light only days after Justice Secretary and Lord Chancellor Chris Grayling was in Keighley to talk with police about the battle nationally to combat child sex crime.

He met officers and civilian workers who are on the frontline of the campaign against such offences.