(Sharecast News) - Cluff Natural Resources shot up on Friday after confirming that it has extended the exclusivity period for a farm-out agreement on licence P2252 by one week.The AIM-traded company said discussions with the unnamed "major" international oil and gas firm which was granted the exclusivity period are at an "advanced stage", though they have not yet concluded, with the extended exclusivity now set to expire on 7 February.The initial exclusivity agreement for the wholly-owned licence, which is located to the north west of the Breagh gas field in the southern North Sea and contains the Pensacola prospect, was signed at the end of November.According to Cluff, the licence is home to a number of "high quality" exploration and appraisal targets within Zechstein carbonates, including the Lytham-Fairhaven fractured dolomite appraisal opportunity and the Pensacola Z2 patch reef prospect which the company states is analogous to other producing fields in Europe.Cluff Natural Resources' shares were up 16.20% at 2.91p at 1129 GMT.