The father of one of the schoolboys wounded in an explosion inside a Second World War pillbox says they were lucky not to have lost a hand in the blast.

The two 15-year-old Faringdon Community College pupils had gone to the bunker for a smoke on Sunday afternoon.

But when they threw their cigarette butts into a bucket it exploded, leaving them with serious burns to their hands and faces.

Police are investigating whether explosive material was planted deliberately. Last night they were still appealing for witnesses.

The town’s 62-year-old former mayor, retired colonel John Gillman, has been arrested on suspicion of causing an explosion with intent to cause grievous bodily harm.

The father of one of the boys, who has asked for the teenagers not to be identified, said the pair remained under specialist care at Frenchay Hospital, in Bristol, receiving treatment for severe burns.

He said: “They are changing dressings today, and they don’t know if they’re going to need skin grafts or not.

“We just don’t know at the moment, but I should imagine they are going to be scarred. They’re in a bad way.”

One boy, a talented rugby player, has severe burns on one hand.

The other teenager, a footballer, has burns to both hands. Both have facial injuries.

The dad said up to eight friends usually met in the pillbox, and the bucket appeared sometime on Saturday or Sunday.

He said: “There is a bit of a wood round there and they use it as a den. My son has only been up there a couple of times.

“It is lucky the rest of the gang had not been up with them, but they were so busy over half term, they were too worn out to meet them.

“The lads keep the place tidy and sweep up, but when they went in Sunday there was this pot with cigarette butts on top of it.

“They had a cigarette, as 15-year-old lads do, and put their butts in the pot, thinking that was what it was there for.

“As the butts hit the mixture, it just went bang and there was an explosion."

He suggested the explosion was so loud it was heard throughout Faringdon, with people living a mile away thinking it was a thunderclap.

He added: “The fire officer said it could have been much worse. It is lucky they didn’t lose any limbs or hands.”

“They are both great, normal young lads, both very sporty. They are pretty brave, but that is on the outside. We don’t know what they are thinking.

“They are going to have flashbacks about this. I haven’t pushed my son about it, because if he needs to tell me, he will.”

He added: “I can’t believe it has happened. It’s just mad. The whole summer is spoilt for them.”

Gillman, who served in the King’s Royal Hussars and the Light Dragoons, retired from the Army six years ago. He has been released on police bail pending further inquiries.

Anyone with information should call police on 08458 505505 or Crimestoppers anonymously on 0800 555111.