The company needs 75% of its creditors to agree to the restructuring plans, a threshold it has not yet reached, the source told Reuters on Thursday. Once the threshold has been hit, it can start the official bookbuilding process for the capital raise.

Premier said on Tuesday it was in talks with private-equity backed oil producer Chrysaor and several other parties on alternatives to the restructuring and capital raise plan it announced on Aug. 20.

Premier said last month it was seeking $530 million in fresh equity, of which existing creditors said they would underwrite $205 million in a potential debt-for-equity swap, should Premier find $325 million in fresh equity elsewhere.

The company had a market capitalisation of around 180 million pounds on Thursday and net debt of just under $2 billion.

"The proposed long term refinancing announced on 20th August is in the best interests of all of Premier's stakeholders and has already received very strong indications of equity support," a spokesman for Premier said.

(Reporting by Shadia Nasralla, Clara Denina, Ron Bousso; Editing by David Goodman, Kirsten Donovan)