Production at UK's Laggan-Tormore gas fields delayed to 2015

* Laggan-Tormore project will not be finished until year-end

* Dong says Herje field production in N. Sea delayed to 2017

LONDON, Aug 28 (Reuters) - Britain's Laggan-Tormore gas condensate fields in the North Sea will start production next year, instead of at the end of this year, operator Total E&P UK told Reuters.

Total (NYSE: TOT - news) is developing the two fields off the Shetland Islands in Scotland at a cost of around 3.3 billion pounds ($5.5 billion). As part of the project, the firm is constructing a gas processing plant and export pipeline.

Total E&P UK is the operator of the fields and holds an 80 percent stake in the project, while Dong E&P UK has a 20 percent stake.

"The plan is to finish construction of the project by year end. Once it's at full production we anticipate (production of) 90,000 barrels of oil equivalent per day," the Total spokesman said, without giving a reason for the delay.

However, in its interim results on Wednesday, Dong said the delay was linked to the construction of the gas treatment plant.

In addition, Dong said its Herje oil and gas field in the Danish sector of the North Sea would not start production until 2017, instead of 2016, due to delays by its suppliers.

Britain's oil and gas output has fallen by around two thirds since 2000 as production has declined from ageing infrastructure.

Hopes for a revival have been pinned on significant capital investment over the past few years by oil and gas majors in new projects off the Shetlands and in field life extensions.

(1 US dollar = 0.6026 British pound) (Reporting by Nina Chestney; Editing by Mark Potter)