Exploration and appraisal update

PREMIER OIL plc

("Premier" or "the Company")

Exploration and appraisal update

27 June 2011

Grosbeak, Norway (Premier 20%)

The Grosbeak well 35/12-4 S, which spudded on 24 April 2011, has completed the drilling and testing of the primary well bore and will now be sidetracked to further delineate the extent of the Jurassic oil accumulation. The sidetrack is expected to be completed by the end of July.

Gajah Laut Utara, Indonesia (Premier 65%)

In Indonesia on the Tuna block, the Gajah Laut Utara-1 exploration well has reached a total depth of 4,688 metres in pre-Tertiary basement and is being plugged and abandoned with oil and gas shows. Oil shows were reported throughout a 350 metre thick succession of interbedded sandstones and shales in the Oligocene. However, logs suggest that the majority of these Oligocene sandstones are tight. One zone was sampled and gas was recovered. The well also encountered good quality water wet reservoir rocks within the Miocene sequence and source rocks within the Oligocene. A working oil and gas petroleum system has therefore been established on the Tuna block. The Ocean General rig will now move to drill the Belut prospect. Belut Laut is located approximately 10 kilometres north-west of Gajah Laut Utara, in a separate sub-basin and is an independent test of the petroleum system on the Tuna acreage. The results of the Belut well are expected in early August.

K-27, Pakistan (Premier 15.79%)

The K-27 exploration well, which spudded on 4 April 2011 in the Kadanwari block, has been successful, testing gas with a flow rate of 51.3 MMscfd through a 56/64 inch choke. The operator (ENI) plans to tie the well to the production facility by the end of the third quarter, delivering around 30 MMscfd.

Simon Lockett, Chief Executive Officer, commented

"The Grosbeak appraisal has provided valuable information and we look forward to the results of the sidetrack confirming the size of the oil reserves in the field.

The Gajah Laut Utara well is the first exploration well drilled by Premier in the Tuna acreage and established the presence of a working petroleum system. We look forward to the results of drilling the Belut Laut prospect.

In Pakistan, the K-27 test results are extremely positive providing additional resources and near term production to the Kadanwari asset."

Enquiries

Premier Oil plc 020 7730 1111

Simon Lockett

Tony Durrant

Andrew Lodge

Pelham Bell Pottinger PR 020 7861 3232

Gavin Davis

Henry Lerwill