Endeavour Reports Additional Drilling Success in UK Cygnus Field

Company and its license participants expand leasehold interest in the field

HOUSTON, July 7, 2010 - Endeavour International Corporation (NYSE-Amex: END) (LSE: ENDV) today
announced that a sixth appraisal well has been successfully drilled and
tested in the Cygnus gas field further confirming the field as one of the
largest ever discovered in the UK sector of the Southern North Sea. In
addition, the Department of Energy and Climate Change has awarded Cygnus
field participants interest in P1731 covering blocks 44/11b and 44/12b. This
new license contains additional fault blocks forming a northerly extension of
the Cygnus structure that are yet to be appraised by drilling.

"With the successful completion of this well in the Cygnus gas field, we
are now pursuing an optimized field development concept that will be designed
to accommodate the potentially significant flow rates from this world-class
gas field," said William L. Transier, chairman, chief executive officer and
president. "Our expanded leasehold position will allow us to maximize the
potential of the field and to accelerate first production in a country where
new natural gas supply is needed."

The 44/12a-5 appraisal well achieved a stabilized flow rate of 29 million
standard cubic feet of natural gas per day from 94 feet of perforations in
the Leman reservoir. Analysis of the results from Cygnus well data combined
with seismic data has led to a reserve estimate in the five appraised fault
blocks ranging from a low case of 500 billion cubic feet to an upside of 1.2
trillion cubic feet. The additional fault blocks falling mainly in the new
license could add material volumes once drilled.

Endeavour holds a 12.5 percent interest in blocks 44/11a and 12a and
17.24 percent in blocks 44/11b and 44/12b. License participants are GDF Suez
E&P, the operator, and Centrica.

Endeavour International Corporation is an oil and gas exploration and
production company focused on the acquisition, exploration and development of
energy reserves in the North Sea and United States. For more information,
visit www.endeavourcorp.com.

Certain statements in this news release should be regarded as
"forward-looking" statements within the meaning of the securities laws. These
statements speak only as of the date made. Such statements are subject to
assumptions, risk and uncertainty. Actual results or events may vary
materially.

Investor Relations, Mike Kirksey of Endeavour, +44(0)207-451-2381, or +1-713-307-8788, or UK Media, Philip Dennis, +44(0)20-7337-1516, or Henry Lerwill, +44(0)20-7337-1526, both of Pelham Bell Pottinger