Police yesterday said they had "concerns" after a 16-year-old schoolgirl was believed to have run away with a grandfather nearly three times her age.

Lisa Wright, who was due to sit her GCSEs this week, has not been seen by her family since setting off for school three weeks ago.

Her mother Angela, 45, has distributed "missing" posters around their neighbourhood of Dagenham, east London, fearing the youngster has disappeared with unemployed Nigel Trowbridge, 46.

A Metropolitan Police spokesman said: "We have concerns because of her age and continue to investigate.

"She is 16, so she is old enough to leave home if she wanted to, but we are treating it as a missing person."

He said Barking police were "actively investigating" the disappearance.

Staff at the Jo Richardson Community School noted that Lisa had not arrived on April 28, according to Mrs Wright.

Police found Lisa's perfume and uniform at Mr Trowbridge's flat in Barking, Essex.

Mrs Wright, a dental nurse, claimed her daughter was "completely infatuated" with Mr Trowbridge, a former family friend who is thought to have five children and two grandchildren.

Mrs Wright said she spoke to her daughter last week. The teenager refused to say where she was and has not been in contact since.

Several of her daughter's friends had seen Lisa with Mr Trowbridge in several pubs, according to Mrs Wright.

Mrs Wright told a newspaper: "I don't know what has happened to her. She seems to be obsessed with him, completely infatuated.

"He started coming round to visit the family about 12 weeks ago.

"I had my suspicions that something was going on and we had a big row about it and I thought that was the end of it. Then I found out she had been missing school.

"She did call but she just said that she doesn't care about her exams and that she loves him."