A Heathrow worker held on suspicion of terrorist fundraising is a baggage handler who loads planes, according to The Sun newspaper.

The 43-year-old - one of two British Airways employees under arrest - has an airside pass and access to jets.

His job has alarmed security chiefs and raised fears he was planning to plant a bomb on a BA aircraft.

However, Scotland Yard stressed last night the man had been arrested on suspicion of financing terrorism, not of plotting atrocities.

He was one of three men held at their homes in Slough, Berks, on Wednesday.

It followed the arrest of a 30-year-old BA worker at the company's call centre in Newcastle six days earlier.

Counter-terror police moved in on the baggage handler and the other two Slough men - aged 31 and 32 - after analysing phone calls and emails from the BA call centre worker.

The four men, all British Asians, are being quizzed under the Terrorism Act 2000 at London's fortified Paddington Green police station.

Security chiefs fear they were raising cash for an attack in the UK - possibly on a jet.

A source said "It is a terrifying prospect that any al-Qaeda sympathiser could work airside with free access to planes.

"The consequences don't bear thinking about."

But another source said "People may well jump to the wrong conclusions because of the man's job.

"There is no evidence he had been involved in any plotting to plant a bomb."

BA said last night "We take all security matters seriously. We continue to co-operate with police."