POLICE are expected to take a week to examine a computer seized in a raid as part of the biggest crackdown on child pornography.

Police executed a warrant on an address in the Bank Top area of Blackburn yesterday where they took the computer as part of Operation Magenta. Nobody was arrested.

More than 70 warrants were issued nationwide with officers from 34 forces across the UK involved in early-morning raids.

The operation is being jointly led by Hertfordshire Constabulary's child protection and investigation unit and the abusive images unit from Greater Manchester Police.

In Lancashire two warrants were issued -- in Blackburn and Morecambe.

Leading the inquiry, Detective Inspector Peter Tracy of the major crime unit said: "We seized the computer as we believe it could be used for evidence.

"Nobody has been arrested and we will wait to see what we find on the computer, which could take a week."

Operation Magenta focused on paedophiles who use chatrooms to advertise and exchange images of children being abused.

Police said the scale of the operation underlined their determination to crackdown on people who distribute indecent images of children.