AN inquiry was under way last night into how two North-East teenagers were able to carry a ten-inch machete aboard a holiday jet.

Cameron Chapman, 18, said he and his brother did not deliberately smuggle the lethal weapon in their hand luggage on the nine-hour flight back from the Dominican Republic.

But he said the knife was not detected by security officers in the republic or at Manchester Airport.

The Department of Transport said it was concerned about the apparent security lapse, and would be investigating.

Cameron knew that his 14-year-old brother, Scott, had bought the machete as a souvenir for a family member, and knew it was in a plastic carrier bag he was using for his hand luggage.

The bag, along with the family's other hand luggage, was x-rayed at the airport, but no one said anything to him about the knife.

It was only when they were airborne that he remembered the machete and the possible consequences of having it.

He did not tell his mother, Jackie, until they had landed at Manchester and had gone through customs, where an officer helped them with their luggage.

Ms Chapman, 53, of Stockton, noticed he had become agitated on the plane home from their two-week trip.

She said: "Cameron started pacing around and looking a bit worried. I asked him if he was alright. I just thought it was the announcement that had worried him."

When Cameron told her about the knife, Ms Chapman panicked, fearing her sons would be arrested and could be in serious trouble.

She said: "I could not believe that they had been so stupid and that I had been sitting there for nine hours with this machete up above my head.

"I was also angry. The machete was just a souvenir but it just shows how easy it would be for someone with terrorist intentions to get aboard a plane."

Cameron said: "I just forgot about it. We were not asked any questions about whether or not we had anything sharp or dangerous and the bag was x-rayed."

A spokeswoman for the Department of Transport said it was very concerned by the incident. Officials plan to speak to the family.

She said: "Provision of aviation security is a host-state responsibility under international law.

"We would like more information from the passengers involved.

"It is a matter for the Dominican Republic, but we do try to work with these countries and would like to know more about the alleged breach."