At the time of the award, Blocks 98/11b and 98/12 in the English Channel included an area adjacent to the Colter South discovery.
The acreage boundaries were subsequently amended by the UK Oil and Gas Authority, which meant the blocks no longer were next to Colter South nor contained the targets that interested UOG and its partners.
It said most of the Poole Bay area is now under landward jurisdiction following the boundary amendment.
As a result, the more prospective areas in Blocks 98/11b and 98/12 cannot now form part of the area offered to the group.
The decision does not affect the Colter and Colter South Discoveries in Block 98/11a (Licence P1918).
Brian Larkin, UOG's chief executive, said: “Should the opportunity arise in the future to bid for the areas adjoining Colter South we will examine that very closely.
"Overall, the 31st Licensing Round has been very successful for United, with the award of four highly prospective blocks in the Central North Sea (Licence P2480).
“This licence covers an area of c. 500sq km, and includes the Zeta prospect, which United estimates could contain over 90 million barrels of in-place oil."
UOG shares are suspended at 4.05p, though Baron Oil fell 12%.