Imperial Sugar said it was in "productive discussions" with insurers over claims on the fatal explosion which closed its core Port Wentworth refinery, leaving the group scrambling to remain in the black.

The US sugar refiner said it had received a further $15m from its insurers in February, taking total payments so far to $125m.

However, that takes payments to only a little over half the refinery's estimated rebuilding costs of $200m-220m. The group says its policy for the refinery, in Georgia, US, also covers "business interruption" and some other costs.

Investors have been concerned over the level of compensation Imperial will receive from insurers, and in particular how much it will negotiate for the impact on its earnings, which in the first quarter registered an underlying $580,000 loss compared with a $12.3m profit a year before.

Cash balances slip

Imperial said that the insurance advances received so far "were not identified with any specific coverage" under its policy. The latest payment has helped the group's cash balances, which halved to $35m during the last three months of 2008.

Group chief executive John Sheptor said that he was "pleased" with progress on rebuilding the refinery, which is set to be restored to full operation in the autumn.

"The foundation of the new silos was completed in February and substantial portions of the structural steel, walls, ceilings and floors for the packaging and administrative buildings have been erected," Mr Sheptor said.

Imperial is appealing against an $8.78m fine imposed by the US Occupational Safety and Health Administration last July for safety breaches at Port Wentworth and a second plant in Gramercy, Louisiana.

Thirteen people died in the Port Wentworth explosion in February last year.