Imperium Renewables Inc. confirmed the closing of its office in Honolulu, raising further questions about whether the company will go ahead with a planned biodiesel refinery at Campbell Industrial Park.

The company said it is handling some of the work that was previously done in its Merchant Street office at its Washington state headquarters. It would not comment on what will happen with the planned refinery.

"They've consolidated some of the functions into their corporate offices in Seattle," said John Williams, a spokesman for the company.

The closing comes as questions are being raised on whether Imperium will go ahead with the $91 million plant on O'ahu. Earlier this year, Imperium tabled an initial public stock offering that would have provided financing for projects in Hawai'i and elsewhere. Last month, the Seattle Post-Intelligencer reported Imperium had laid off some of its corporate staff.

Imperium had hoped to have the 100 million-gallon-a-year facility up and operating by the end of this year, with pipelines ready to supply a 110-megawatt Hawaiian Electric Co. generating facility that's to be built nearby.

Imperium has a contract to be the exclusive biodiesel supplier for the HECO plant through 2011.

HECO spokesman Peter Rosegg said the utility was aware of the latest action by Imperium, but that nothing has changed for now.

"We have a contract with the company and expect that contract to be honored," Rosegg said.

In January, Williams said the company intended to fulfill its contract with HECO and that Imperium was evaluating a range of methods to enable continued project development.

Last week, he said the company was not prepared to say more.

"The company has not made a final announcement on the planned Hawai'i facility," Williams said.