(Adds details on discovery, share movements)
April 2 (Reuters) - Premier Oil Plc and Falkland Oil and Gas Ltd said they made an oil and gas discovery at a well in the Falkland Islands, the first in a nine-month drilling campaign.
The companies said the discovery of 81 feet of net-oil bearing reservoir and 55 feet of net gas-bearing reservoir at the Zebedee well was better than expected.
Analysts for brokerage Stifel, however, said the uncertainty around the development of the Sea Lion project meant the discovery was unlikely to change the picture in the North Falkland basin.
"A full appreciation of the significance of today's result may have to wait until the conclusion of the drilling campaign later this year."
In November, Premier Oil scaled back its Sea Lion oilfield project after struggling to find a partner and weak oil prices put pressure on the company to cut costs.
Shares of Premier Oil rose as much as 6.5 percent, while those of AIM-listed Falkland Oil gained 26.8 percent before reversing course to fall 17 percent to 29.48 pence in early trade on Thursday.
Premier owns 36 percent of Zebedee, while Falkland Oil holds 40 percent and Rockhopper Exploration Plc the remaining 24 percent.
Rockhopper's shares rose 12.8 percent, before paring gains to trade up 1.6 percent at 64.64 pence on the London Stock Exchange.
Drilling for oil and gas in the resource-rich Falkland Islands by London-listed companies remains controversial as a decades-long row between Britain and Argentina over the sovereignty of the islands has not been resolved.
Zebedee is the first of six wells that are part of a drilling campaign started in March by Rockhopper and Falkland Oil and involves Premier Oil and Noble Energy Inc.
The companies, which announced the discovery in separate statements, said the well will be plugged and abandoned as a successful exploration well and the rig will be moved to the southern part of the North Falkland Basin.
Reporting by Abhiram Nandakumar in Bengaluru; Editing by Anupama Dwivedi