The number of samples held on the DNA database will rise to 4.25 million within two years, the Home Office says.

There are three million samples held at the moment, with some of the expansion due to law changes in 2001 and 2004.

Suspects arrested over any imprisonable offence can have their DNA held even if they are acquitted.

The database includes 139,463 people never charged or cautioned with an offence, separate Home Office figures obtained by the Liberal Democrats show.

Matches using newly-lawful DNA samples have been made to 88 murders, 45 attempted murders, 116 rapes and 62 sexual offences.

More than 198,000 samples are held that would have had to be destroyed under the old law.

In all, 7,500 of these have been matched to 10,000 offences.

The Home Office report showed that 5.24% of the UK population now has a DNA profile held on the database. This compares with an EU average of 1.13% and 0.5% in the US.

The number of crimes solved through DNA technology has quadrupled over the past five years.

There has been a 74% rise in the number of crimes where potential DNA material is collected, and a 75% increase in the number of matches of suspects to crime scenes.

Police can now track down offenders by matching samples with other family members who may be on the database.

The number of samples on the database has trebled in the last five years - beyond the target set by the Home Office.

It includes more than 15,000 volunteers, including victims of crime, who gave samples in response to police appeals.

Liberal Democrat home affairs spokeswoman Lynne Featherstone said: "There is no purpose or justification for keeping the DNA record of anyone who is not charged with an offence.

"This is an intolerable infringement of liberty and personal privacy.

"We cannot be absolutely certain that there will be no misuse of the DNA database.

"There are no real safeguards in place to control it.

"With the growing concern about racial profiling and disproportionality in criminal investigations, the need to keep innocent people on the DNA database is questionable."

Shadow Home Office minister Damian Green said: "If the government wants a database that has the details of everyone, not just criminals, they should be honest about it.

But he added that a DNA database was essential "to reverse the trend of rising crime in Britain".

In a case last November, a 50-year-old builder was found guilty of a murder and rape he committed in Essex 27 years ago.

He was stopped for drink driving in 2004 and his DNA matched a sample on the database taken from the original crime scene.

Several English forces have also been testing a mobile laboratory which cuts the time taken to produce DNA matches.

However, police identifying the bodies of victims of the Asian tsunami found samples can degrade, noting that it may not always be possible to identify people from their DNA.