The family of a British construction worker killed by his kidnappers minutes after a joint UK and Nigerian rescue operation stormed their compound yesterday praised the soldiers who tried to save him and said the Government had been right to send them.

Quantity surveyor Chris McManus from Oldham was shot six times as the special forces tried to save his life, but they were under AK-47 fire from the kidnappers at the compound in Nigeria's north west city of Sokoto. His Italian colleague Franco Lamolinara was also killed.

His family said the seven British special forces soldiers and the Nigerians had risked their lives to save him after nearly 10 months of captivity at the hands of Islamist extremists. "We hoped until the end for a positive out-come as we are sure did Chris and Franco. They were always in a dangerous situation from the time of their kidnapping.

However, the sequence of events, particularly over the last few days of their lives, played out in such a manner as to make it a hopeless one," his mother Laura said.

"We accept that the decisions reached and taken by the authorities were the only ones possible based on the information available."

Wiltshire and Swindon coroner David Ridley recorded a verdict of unlawful killing and said: "Chris died from the result of a devastating gunshot wound to the head."

The hearing in Salisbury heard the soldiers stormed the building after intelligence in previous days told them that Mr McManus, 28, was there with Mr Lamolinara.

The go-ahead for the operation had been given by Cobra – the Government's crisis committee – at 11.15, just 45 minutes before it started, after a senior officer had reviewed the evidence and there were fears for the men's safety.

The British team, sent to the area the previous day, burst into the compound on March 8 last year, senior investigating office detective chief inspector Grant Mallon said. They came under small arms. The men killed at least one militant and then Mr Mallon said they heard further shots in the north west area of the compound. A post-mortem found Mr McManus died from a single gunshot wound to the head, the hearing was told.

The failed operation caused a diplomatic row between Britain and Italy after Italian President Giorgio Napolitano said it was "inexplicable" that Downing Street had not alerted Rome to the rescue plan.