POLICE raided a house in Nelson as part of a crackdown on the use of birth certificates of dead children to get false passports.
Three houses in Lancashire were raided as part of the national Operation Wisdom led by the National Crime Squad.
One person was arrested as a result of the raids at homes in Nelson, Chorley and Preston.
And more than 40 raids were carried out on homes across the country in a bid to crack down on the scam.
Twenty-one people suspected of illegally obtaining passports were arrested as part of a nine-month investigation by the National Crime Squad's immigration crime team.
Its investigation revealed that birth certificates belonging to dead children were being duplicated and allegedly used to create new identities.
Police said the UK Passport Service contacted the National Crime Squad after its own inquiries identified a number of passports now known to have been obtained fraudulently.
Det Supt Andrew Wood, of the NCS who is leading the immigration crime team, said: "We are delighted with the results of this operation.
"There is no doubt that yesterday's events will cause much distress to parents whose children died some years ago and it is regrettable that these events have rekindled their grief."
Beverley Hughes, Home Office Minister, expressed her sympathy to parents affected by the investigation, but said: "Significant progress is being made in the fight against those who hijack identities through such abhorrent means.
"Its success sends out an unequivocal signal that those who hold illegally obtained passports or seek to gain passports will be tracked down and put before the courts."
Some of those arrested were also suspected of fraudulently claiming benefits and obtaining driving licences using false identities.
The investigation involved the General Registry Office, Department of Works and Pensions, the Driver and Vehicle Licensing Agency, the NHS, the Inland Revenue and the Immigration Service.
Thames Valley Police arrested four people; Leicestershire two; Sussex three; Hertfordshire two; Humberside four; Lancashire one; South Wales two; Strathclyde one; Cambridgeshire one; Northamptonshire one.
It was also understood a number of people were arrested in the West Midlands and in London, but figures had not been released.
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