Grace Forster was shot through the back

Alex Wijeratna spoke of his concerns after BBC News Online revealed that two divers were shot in a robbery on Pemba Island, Tanzania, on Friday.

Grace Forster, 18, from Whittlesey, Cambs, is in hospital and Robert Scott, 20, from Bristol, has been discharged.

Mr Wijeratna said his diving group in Pemba was attacked in February.

He said the boat he was on was attacked by machete-wielding bandits who robbed him and his group of about $5,000.

Pemba is really paradise, but people need to know about the potential hazards and security risks before they go out there Alex Wijeratna

"The captain was hit round the head and side and needed 50 stitches," Mr Wijeratna, 34, from west London, told BBC News Online.

"We were searched and the boat was ransacked. It was total terror.

"Pemba is really paradise, but people need to know about the potential hazards and security risks before they go out there."

He said he was speaking out because he had thought it was a random thing.

"We were given the impression it was a one-off but it sounds like something slightly systematic or pretty scary," said Mr Wijeratna, who was travelling with Pemba Afloat, which runs diving groups.

The group of 25 diving enthusiasts who were attacked on Friday had been organised and assembled by marine conservation group Frontier.

Frontier said one of the victims had been discharged from hospital in Dar es Salaam and the second was expected to be released some time on Sunday.

Friday's attack on the island of Pemba took place at about 7.30pm local time.

'Bullet just missed spine'

Seven attackers armed with guns and machete knives stole Frontier's boat and engines, as well as money and personal possessions, Frontier spokesman William Hedley-Miller said in a statement.

Ian Forster, father of Grace Forster, said: "The bullet entered Grace's left side and travelled through just missing her spine. It could have ended her life."

He said both victims were expected to be flown back to the UK soon.

Mr Forster said he hoped Frontier would look into security issues.

"This needs to be thoroughly checked out," he said.

"My concern as a parent is what are they going to do to stop the same thing happening again?"