Britain's oil regulator has launched a licensing round for access to 813 oil and gas exploration blocks or partial blocks in the British part of the North Sea, it said July 25.

The Oil and Gas Authority's (OGA) 30th licensing round offers access to mature areas in the Southern, Central and Northern North Sea, the West of Shetland and East Irish Sea.

The round is open for 120 days until Nov. 21, the OGA said in a statement. Decisions will be made in the second quarter next year.

Britain wants oil and gas drillers to recover pockets of gas that are more difficult to reach in a part of the North Sea where drilling for fossil fuels started over 50 years ago.

The OGA has said that some 3.8 trillion cubic feet (Tcf) of tight gas remain in the southern North Sea, one of the world's oldest offshore gas extraction areas that has produced more than 40 Tcf.

Drilling activity in Britain's North Sea has been at a record low for two years as weak oil prices make projects less attractive.

The basin is estimated to have billions of barrels of oil left for extraction, worth around 200 billion pounds (US$250 billion) for British government coffers, which the government is keen to see developed.