Tullow Oil shares plunged after the group admitted last year's output was lower than forecast.

The FTSE 100 group's share price fell 104p, or 7.15 per cent, to £13.51 at 9.00am, as results for the financial year ending 31 December 2011 proved underwhelming. 

Tullow is the second oil company in as many days to witness a dramatic fall, after rival Essar Energy lost over a quarter of its value on Tuesday.

Tullow's main producing asset, the Jubilee field in Ghana, averaged just 66,000 barrels per day (bpd), around half the 'field plateau rate of 120,000 bpd'. The group said it expected average production to increase to between 70,000 and 90,000 bpd in 2012, still some way short of capacity.

Jubilee's weak performance dragged down group production to an average of 78,200 bpd - outside the range of 79,000 to 81,000 bpd forecast by Tullow in November last year.

However, the London-based firm was able to report sales revenue of US$2.3 billion (£1.5 billion) for the year ending 31 December 2011.

Josh Raymond, chief market strategist at City Index, said investors were understandably disappointed with the results, and added, 'Tullow Oil’s share price has also hit technical resistance at around the £14.70 mark, which has put a roof on gains for much of the last year.

'With investors seeing the production outlook for the next year missing forecasts, they have moved to reduce their holdings.'

Tullow CEO Aidan Heavey described 2011 as 'very good' for the group but preferred to focus on the year ahead.

'In 2012 we expect significant progress in Ghana and Uganda as we move forward with Jubilee well remediation and the Lake Albert developments,' he said.

'We have an exciting exploration programme to open new basins, both onshore and offshore, and we hope to extend our reach in Africa and elsewhere along the Atlantic margins with major new partnerships. There is much to look forward to in the year ahead,' he finished.