Lansdowne Oil & Gas went public on Friday and its shares closed up over 20% at £1.05, valuing the firm at almost £22m (32m).

In 2004 a Texas court upheld a $6.4m fine against Ramco following a case taken by Houston-based AngloDutch.

Anglo-Dutch had filed a suit against Ramco and other defendants including Halliburton, which had both considered drilling at an Anglo-Dutch oil field in Kazakhstan in 1996. They were accused of giving confidential information about the field to a third party, which bought rights to drill the field in 2001.

Halliburton was fined $64m.

The ruling was appealed by Ramco, and a final determination has not been made.

Scotland-based Ramco Energy came close to collapse when its massive investment in the Seven Heads gas project off Kinsale failed to deliver on projections. The company had borrowed almost 100m from Bank of Scotland in 2002 to develop Seven Heads, much of that secured against gas production from the field that never materialised.

Last year Ramco put its Irish offshore assets under the control of Lansdowne Oil & Gas following a £750,000 fundraising. The assets include a 19.25% interest in a frontier licence in the Donegal Basin, as well as four Celtic Sea licensing options. The operator of the Donegal licence, Lundin, is expected to begin exploratory drilling there during the summer.

Last week, Anglo-Dutch claimed it had got a court order preventing Lansdowne from floating, but a spokesman for Ramco denied this and described the AngloDutch statement as ?misleading". He said no such order had been issued, noting that the court had asked Ramco to deposit certain documents with it, which it had done, but that there was no instruction relating to Lansdowne Oil & Gas.

Ramco cannot sell its shares in Lansdowne Oil & Gas until the ruling is final.

The Ramco spokesman said that if the company loses the appeal, it can opt to take the case to a higher court.