Abu Dhabi-based Dolphin Energy plans to borrow at least $3.45 billion to help take the company to its next phase and has appointed Royal Bank of Scotland (RBS) to advise, a company source said on Thursday.

'Royal Bank of Scotland is the financial advisor for the final project financing,' a Dolphin source told Reuters, declining to be identified as the information is not public.

'It will be at least $3.45 billion, but the final amount has not been decided yet.'

The source declined to give a timeframe or say what type of financing it would be seeking. An executive at Royal Bank of Scotland declined to comment.

The Dolphin project linking Qatar's giant North Field with the United Arab Emirates and Oman was the first cross-border gas project in the Gulf Arab region.

It has pumped around 2 billion cubic feet a day of gas from Qatar to the UAE since February. The final cost of the entire Dolphin project was around $4.8 billion, Dolphin general manager Ibrahim Al-Ansari said on Tuesday, up from initial estimates of around $3.5 billion.

Dolphin raised about $3.5 billion in 2005 through a $2.45 billion conventional facility and a $1 billion Islamic loan, according to the company's website. The financing matures in 2009.

The source said Dolphin was looking for additional financing to take the company beyond 2010, without being more specific.

Mubadala Development Co, run by the government of Abu Dhabi, owns 51 per cent of Dolphin, while France's Total and US Occidental each have a 24.5 percent stake.-Reuters