A BAN on flights containing unaccompanied air freight from Somalia and tighter restrictions on transporting toner cartridges were announced as the Government attempted to tackle the latest terror threat.

Home Secretary Theresa May announced the measures, which came into force at midnight, as she updated MPs on the air cargo bomb plot.

But a Huddersfield aviation expert said he hoped the new alert would not cause too much inconvenience.

Dr David Warnock-Smith said it was clearly aimed at disrupting world freight rather than passenger airlines.

Mrs May told MPs the two bombs identified in the plot originated in Yemen, but said suspending freight flights from Somalia was necessary because of a possible link between terrorists in the two countries.

Toner cartridges larger than 500g (17.6oz) will also be banned from hand baggage on flights departing from the UK and also on cargo flights unless they originate from a regular shipper with security arrangements approved by the Department for Transport, she said.

Mrs May told MPs: “We are in a constant battle with the terrorists.”

Dr Warnock-Smith, a senior lecturer in air transport at the University of Huddersfield, says he believes the new threat is targeted at disrupting worldwide freight.

And although many passenger airlines do carry some freight cargo, the majority of flights used by Huddersfield passengers are for tourists only.

“I think people should be reassured they will not be too adversely affected by this.

“People travelling from Huddersfield on holiday flights from the likes of Manchester and Leeds/Bradford should feel safe. There are already strict security measures in place and there should not be massive extra disruption in the wake of the weekend events.

“In the short term, there may be one or two problems – especially if an airport has to be sealed off, but most of our airports are geared towards passengers and not freight. It seems the terrorist wants to disrupt the international freight trade”.

Air travellers face no let up in stringent security checks after it emerged one of the cargo plane bombs was transported on passenger aircraft before being found.

There are also fears that more explosive devices may still be at large.

A bomb found in a car at Belfast International Airport had been there for almost a year.

Staff checking vehicles at the long-stay car park found a pipe bomb attached to cans of petrol. But it failed to detonate properly because of an apparent fault with the timing device.

It is believed the car, a Toyota Carina, had been there since last year and the bomb was meant to go off at the time the car was abandoned.

Scores of passengers on returning flights and unable to drive home had to be accommodated a nearby hotels on Saturday because of the alert.