FRESH bids to unlock what may be a large oilfields off the coast of Scotland have got underway.

Seventeen firms have been granted licences to probe for oil and gas in under-explored areas of near St Kilda, the North Sea, and the waters east of Shetland.

A study has previously said that there could be fossil fuel reserves with an estimated value of more than £1 trillion based on rock formations in Rockall alone, but so far wells drilled in the area have not been productive.

The Oil and Gas Authority's (OGA) 29th licensing round was the first in two decades to focus solely on under-explored areas of the Rockall Basin, Mid-North Sea High and part of the East Shetland Platform.

One oil expert said it was "very encouraging" to see firms bidding for the right to carry out further exploration of the areas, which have been divided into 111 blocks.

Three "firm" commitments have been given to exploit new wells, with the option to drill for more on the table.

Alexander Kemp, Professor of Petroleum Economics and Director of Aberdeen Centre for Research in Energy Economics and Finance, said: "These are all frontier areas and he number of blocks which have been allocated is very encouraging, given the relatively low prices for oil and gas at the current time."

Professor Kemp believes that a decision by the OGA to release seismic data from the seabed would likely have spurred firms on to take a risk on finding an oil bonanza in what has been traditionally difficult areas to work.

He said: "It could be that the provision of seismic data has encouraged some of the applications for the licenses. Given that these are frontier areas, the number of blocks awarded is encouraging.

"These three areas are very much relatively unexplored. In Rockall there was one discovery but it was not viable. But now we are seeing firms willing to take the risk of exploring there, there may be something in the data of interest."

The licenses are for exploration only, with separate licenses need to begin drilling operations. However, Professor Kemp said that the OGA was highly unlikely to refuse firms if significant amounts of fossil fuels are found.

The licensing round attracted applications from 24 companies before it closed in October. Licences were granted after the UK Government carried out seismic work in the area.

As part of the process all firms have been screened to ensure they are financially healthy and have the correct technical, safety and

environmental capability.

Those recommended for the offer of an award also had to prove they had sufficient financial backing for the commitments they would be taking on.

Andy Samuel, OGA chief executive, said: "We are particularly pleased to see firm well commitments, the targeting of new and under-explored plays and first-time entrants to the basin, alongside a number of established companies, which will help stimulate further activity and value creation.

"While exploration activity has undoubtedly suffered as a result of the difficult market conditions, we are now seeing highly encouraging success rates and finding costs on the UKCS (UK Continental Shelf). This is testament to the value of a robust and focused exploration strategy with commitment from industry, government and the OGA.

"The 30th offshore licensing round will focus on mature areas and is expected to be the most significant offshore round in recent decades."