(Sharecast News) - Cluff Natural Resources announced on Thursday that, further to the provisional award of licences in the UK's 30th Offshore Licencing Round announced on 23 May, it has now received and accepted the formal award by the UK Oil and Gas Authority of the six licences covering a total of 10 full and part blocks.The AIM-traded firm said the formal start date of each of the licences would be 1 October.It said the initial phase of each licence would be four years, other than licences P2424 and P2428 where the initial phase would be three years.With the exception of blocks 47/10d and 48/6d, where the Parkmead Group was operator, Cluff said all blocks had been awarded to CLNR on a 100% equity position.The board said it viewed the blocks as "highly prospective", with many containing undeveloped discoveries and exploration upside, which "significantly enhanced" both the pipeline of potential drilling opportunities and the overall prospective resources associated with the company's portfolio.It said the Southern North Sea blocks awarded to CLNR contained a number of drilled discoveries, undrilled prospects and leads with an estimated combined unrisked P50 prospective resource of approximately 1.9 TCF net to CLNR.The firm work programme associated with Phase A of the initial term of the licences was restricted to data acquisition, reprocessing and subsurface studies, and was focussed on providing greater clarity around prospect volumetrics and risk.In the Central North Sea, it said Blocks 22/24f and 22/25g were located in a relatively under-explored area, adjacent to the large Marnock-Skua field.The blocks contained the Tesla Discovery - well 22/24a-11 - in the Pentland Formation, and the low risk Dewar prospect in the Forties Sandstone.Previous operators have also proposed leads in the deeper Jurassic formations which required further assessment during the initial phases of the licence.Block 22/19f is located in the Central North Sea and contained multi-level oil prospectivity in the proven Fulmar, Skagerrak and Rotliegend formations, the board explained.Previous operators had reportedly identified a large number of prospects and leads which required further assessment during the initial phase of the licence."We are delighted to have received and accepted the formal award of these additional licences by the UK Oil & Gas Authority following the announcement of provisional awards in May 2018," said chief executive Graham Swindells."We believe these licences to be highly prospective and we are in the process of commencing technical work to accelerate their development."CLNR was one of the most successful applicants in the UK's 30th Offshore Licencing Round and the extent of the awards further establishes our position as a natural resources investing company and underlines our commitment to the UK and to the North Sea where we see significant value."