Airport security chiefs have been ordered to remain vigilant, after an undercover journalist apparently smuggled a meat cleaver and dagger onto a flight from Heathrow.

Transport Secretary Alistair Darling said he had demanded an urgent report into the incident from the British Airports Authority (BAA).

It is the second security lapse highlighted by the media this week, coming days after a television journalist took a replica pistol on to a flight.

A BAA spokesman said it was taking the issue very seriously, but that the detection of deliberately concealed weapons was very difficult.

'Complacent'

The meat cleaver, which was hidden in a wallet, and the four inch dagger, disguised as a hairbrush handle, were taken on board a British Airways Heathrow to Manchester flight.

I can't stress enough the importance of the aviation industry being as vigilant as they possibly can

Alistair Darling

Neil Wallis, editor of The People newspaper which carried out the investigation, said the security lapse exposed a serious risk to passengers.

"The scary thing is that people are complacent," he said.

"The idea that less than a week before September 11, at a time when every security organisation is saying to be careful, we can simply stroll through the busiest airport in Britain with weapons is a major problem."

'Constant review'

Mr Darling said he had asked BAA officials for an explanation.

He said: "I can't stress enough the importance of the aviation industry being as vigilant as they possibly can."

A BAA spokesman said: "We are concerned these items were apparently taken through our security, but items deliberately concealed can be difficult to detect.

"We keep our security under constant review and we are actively seeking to improve security processes through new technologies, working with the government and research agencies."

BAA added that thousands of banned items are confiscated from passengers on a daily basis and that all hold luggage is thoroughly screened.

'Concerned'

Earlier this week it emerged that a replica 9mm semi-automatic pistol was apparently taken aboard a flight from Heathrow to Edinburgh in the holdall of a Meridian Television reporter.

Another journalist was said to have carried a pair of scissors, hidden in a personal organiser, onto flights from Gatwick and Southampton.

The Department of Transport said the apparent security breach should never have happened and that Mr Darling was "extremely concerned".