UK nuclear delay may hit energy security - engineers

* Delay to EDF Hinkley plans "would boost gas"

* Hinkley approval held up by Fukushima - EDF

* UK 2025 nuclear target "challenging" - engineers

LONDON, Sept 11 (Reuters) - Any delays to building the UK's first new nuclear plant since the 1990s could hold up other atomic projects and deepen the country's dependence on potentially insecure fuel imports, a panel of British civil engineers said on Tuesday.

The engineers told British parliamentarians they were worried about threats to the timetable for EDF Energy's planned nuclear reactor at Hinkley Point in the English county of Somerset.

France's EDF, the largest nuclear power producer operating in Britain, originally said it wanted to open the plant by 2018. But after Japan's Fukushima nuclear disaster last year, the company said the approval for the reactor design has been held up by regulators and the start date has slipped.

When asked whether any delay would hit Britain's energy security - its ability to rely on secure, close-at-hand energy supplies - one member of the panel, John Earp, replied: "Yes ... If there is a significant slip (to EDF Energy's start-up date) then the alternative is probably a move toward gas."

That extra demand would likely need to be met by foreign supplies, Earp, a fellow at the Institution of Civil Engineers, told the British parliament's energy and climate change committee.

A significant delay at Hinkley could also affect other nuclear projects, threatening government plans to have more new nuclear plants up and running by 2025, the panel added.

"We have taken the view ... we would need a fair wind behind us to meet the 2025 (goals)," said Alasdair Reisner, director of external affairs at the Civil Engineering Contractors Association.

Companies planning to build new nuclear plants in Britain are hoping to generate about 16 gigawatts of new capacity by 2025, a goal the government says will help the country meet its emission reduction targets and cut its reliance on fluctuating gas prices.

Due to the UK's dwindling gas supplies the country has already become a net importer of the fuel, leaving the country dependent on supplies from sometimes remote and politically unstable regions.

Gas currently produces around 20 percent of the UK's power. Another 20 percent comes nuclear power stations but new plants are needed as older stations are shutting down.

EDF has already announced details of the planned Hinkley plant but has said it will make a final decision on whether to go ahead with the project before the end of the year.

The company also said it was open to the idea of seeking investment partners project after its half-year results showed its debt levels had soared to almost 40 billion euros ($51.14 billion).