* Norpipe maintenance planned for June 3-June 24
* Gas work to force oil production shutdown
* Fields in greater Ekofisk area to be affected
OSLO, April 25 (Reuters) - Oil production from the Great Ekofisk area in the North Sea could be reduced by up to 5 million barrels of oil in June due to a shutdown of the Norpipe gas pipeline for work, industry sources said on Thursday.
"Ekofisk has to shut down all production, including oil, if they cannot evacuate gas via Norpipe," one source familiar with Norway's offshore oil and gas infrastructure said.
"This also affects other fields delivering gas to Norpipe in the area," he added.
Gas to Norpipe is fed from Conoco Phillips-operated Ekofisk, Eldfisk, Tor and Embla fields, as well as from BP's Valhall and Hod, and Talisman's Gyda, according to the data from Point Carbon, a Thomson Reuters company.
Production from the seven fields in February totalled 5 million barrels of oil. Hod field has not produced any gas or oil since the beginning of this year.
ConocoPhilips, BP and Talisman were not immediately available for comment.
Norway's gas system operator Gassco also declined to comment on specific field maintenance, but it has previously said Norpipe, which delivers gas to the Emden terminal in Germany, will be shut from June 3 until June 24.
The pipeline will be shut to install a by-pass around the compressor station B11, which is going to be dismantled later.
Norpipe has a maximum capacity of 35 million cubic metres (mcm), but it has been running at an average of 15 mcm per day during the last two weeks.