Three people who were arrested yesterday after one of the first ever police investigations into internet banking fraud have been released on bail.

The suspects were held for questioning after officers from the National Crime Squad swooped on addresses in Buckinghamshire, Bedfordshire and Northamptonshire.

The allegations centre on fraudulent applications made to the internet bank Egg.com. Staff at the bank have worked with police over the last six months to help with the investigation.

Egg said that no money was stolen and customers were not affected. Egg's operations director, Gary Clifton-Marshall, told BBC Radio 5 Live that the alleged fraud related to criminals attempting to establish bogus accounts to access funds. "Fortunately we have robust systems in place that will prevent this taking place," Mr Clifton-Marshall said. "In no way have any of our customers suffered."

Officers seized computer equipment, cash and drugs in the raids, which took place yesterday. An NCS spokesman said the arrests came after an investigation into fraudsters who were targeting internet banks to gain "considerable sums of money". The suspects were bailed for "several weeks", he added.

Egg, which has about 1.1m customers, said that earlier this year "fraudulent applications" were made to the bank in order to obtain money, but there was no breach of security and no money was obtained.

Egg shares fell more than 4% in early trade today but later recovered.