Exploration Drilling Update

PREMIER OIL plc

("Premier" or "the Company")

Exploration Drilling Update

25 June 2012

Coaster well (28/10a), UK

The Coaster exploration well on UK Block 28/10 (Premier equity 50%) has reached a total depth of 5684 feet and is being plugged and abandoned as a dry hole.

A total of 17 feet of Tertiary sandstones were encountered but these were shown to be water wet on logs.

The next exploration well to be drilled by Premier in the North Sea is the Spaniards East well on UK block 15/25a, which is due to spud in September.

Benteng-1, Indonesia

The Benteng-1 exploration well on the Buton Block (Premier equity 30%) in Indonesia has reached a total depth of 12424 feet and is being plugged and abandoned as a small but potentially commercial oil discovery.

Good oil shows were encountered over a 111 feet interval from a depth of 2375 feet and initial log analysis indicates a 15 feet oil bearing Tertiary limestone reservoir.

Benteng-1 is the first well to discover hydrocarbons in the frontier Buton Basin. The well was drilled to test two play types, a shallow anticline and a deeper fault dependent trap. The hydrocarbons were discovered in the shallow play type. The results of the well will now be integrated into the existing data base to determine the commercial viability of the discovery and the follow on potential in the shallow play type across the Buton Block as a whole.

The next exploration well to be drilled by Premier in Asia is the Chim Sao Northwest appraisal well, which is due to spud in July.

Simon Lockett, Chief Executive officer, commented:

"The Coaster and Benteng wells were both assessed as very high risk pre-drill. Coaster was an important well to drill, given its proximity to the Catcher licence; but in recognition of the risks we took the precaution of farming-out 50% of our equity on a promoted basis. The Benteng-1 results are encouraging as they have established a working petroleum system in a previously unproven basin."

Enquiries

Premier Oil plc 0207 730 111

Simon Lockett

Andrew Lodge

Pelham Bell Pottinger  020 7861 3232

Gavin Davis

Henry Lerwill