More than 30 girls are missing from schools in Bradford despite efforts to track them down, MPs have been told.
The government has established a Forced Marriages Unit
Authorities suspect 33 children from the city have been "taken abroad to participate in forced marriages", Labour MP Keith Vaz said.
Children's minister Kevin Brennan told the Commons Home Affairs committee that the issue was a "serious concern".
The government had identified 14 other areas with suspected high rates of so-called "honour violence", he added.
Mr Vaz, the committee's chairman, said that he was "shocked" by the figures.
Mr Brennan told MPs that Bradford City Council had lost track of 205 youngsters aged under 16 from its school rolls in 2007.
Following inquiries, 172 were tracked down - but 33 were left unaccounted for.
"What we need to try to do is seek an explanation of what has happened," he said.
Asked whether the police were searching for them, he added: "They should be."
The government investigates 300 forced marriages a year, including about 70 overseas rescue operations.
It has established a special Forced Marriages Unit which mounts clandestine rescue operations predominantly to help British women forced into relationships in Pakistan.
Forced marriages are different to Asian traditions of arranged marriages which are freely-agreed matches, facilitated by families.