Insurers have warned that smaller construction companies must tighten up their safety records, or face the threat of higher premiums.

This follows the release of a study by construction union, Ucatt, which said that deaths on construction sites had risen by 25% over the past year to a total of 75.

Phil Bell, group casualty director at Royal & Sun-Alliance, said: "Premiums take into account safety and the likelihood of an accident on site. Ultimately, if claims continue to rise, premiums will rise as well."

Other insurers have said that companies with limited resources face problems of maintaining adequate health and safety.

Bill Friar, principal risk consultant at Zurich Risk Services, said: "Resources tend to match the size of the organisation. But legislation has been laid out. The responsibility lies with the employer."

Friar said that the Corporate Manslaughter Bill, currently working its way through parliament, would be welcomed by the insurance industry if it succeeded in focusing the mind of management staff.

"It is the stick before the carrot," he said.

But despite the danger of escalating premiums, Bell insisted that withdrawing cover entirely was unlikely.

"We are in the business of paying claims," he said, adding that the rise in fatalities was part of a downward trend. "We cannot change premiums based on one year's figures."