British scientists said Friday they have applied to the government for permission to carry out a field trial of genetically-modified plants that can produce fish oil.

Agronomy company Rothamsted Research has engineered Camelina plants -- also known as false flax -- to produce two key omega-3 fatty acids contained in the oil.

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have been shown to have a beneficial effect on cardiovascular health in humans.

But with fish stocks declining, and existing oil supplies being used extensively in fish farming, scientists want to find a new source.

After successful tests in the laboratory and the greenhouse, Rothamsted now wants to examine the GM crop in controlled but "real environmental conditions".

The trial is likely to cause controversy in Britain, where public opposition has prevented any GM crops from being grown commercially, although they are imported.

Rothamsted's application to the environment ministry will be examined by experts in a 90-day process that includes a public consultation.

Professor Johnathan Napier, lead scientist on the project, said the company was "very interested in having a dialogue with people" about what it was doing.

Fish produce the two key fatty acids, EPA and DHA, when they consume certain types of marine algae.

Napier's team has effectively cut and pasted genes from the algae into Camelina plants, which are widely cultivated in Europe and North America.

Three varieties of plants have been produced, each spliced with a different number of synthetic genes.

There is growing demand for fish oils for their health benefits but also in intensive fish farming.

Farmed fish do not feed on marine algae and instead are given their omega-3 in the form of fish oil -- a process which uses about 80 percent of all the fish oil available.

Plants such as flax and linseed also naturally contain fatty acids but these are of a different type.

Rothamsted Research describes itself as a charitable company largely funded by state-funded research bodies.