UPDATE 1-Denmark's DONG to build two more UK wind farms

(Adds DONG comment)

COPENHAGEN, Dec 3 (Reuters) - Danish oil and gas group DONG Energy said on Monday it would construct and operate two British offshore wind farms, Walney Island and Gunfleet Sands II, for a total investment of 5.2 billion crowns ($1.02 billion). The Walney Island farm -- 15 km off the West coast of England in the Irish Sea -- will have a capacity of 151 megawatts distributed on 42 wind turbines and is scheduled to go into production in 2010, DONG said in a statement.

Gunfleet Sands II -- in the Thames Estuary off the East coast of England -- will have a capacity of 64 megawatts distributed on 18 wind turbines. Production will start in 2010.

Walney Island is the first stage of a project, under which DONG has the right to build an offshore wind farm with a capacity of up to 450 megawatts on the site.

DONG is already constructing two other offshore wind farms, Gunfleet Sands I and Horns Rev II, which are scheduled for completion in 2009.

Siemens Wind (SIEGn.DE) was awarded the contract to supply wind turbines to the Gunfleet Sands I project earlier this year, DONG spokesman Steen Juul Jensen told Reuters.

Jensen also said that Siemens is the only manufacturer that currently produces a 3.6 megawatt turbine, on which the two new British projects are based.

(Reporting by Karin Jensen, writing by Kim McLaughlin, editing by Will Waterman)