Official advice about eating fish will be reviewed due to environmental concerns, the food watchdog said yesterday.

The Food Standards Agency (FSA) will still encourage people to eat more fish, saying they should usually aim for at least two portions per week.

But it has launched a review of its advice in the light of growing concerns about the sustainability of some types of fish. The FSA will also consider the wider environmental impact of fishing and fish farming.

Its review is likely to focus on which fish people buy, where those fish are caught and how they are caught, a spokesman said.

Statistics show that 52% of the world's fish stocks are fully exploited, which means that they are being fished at their maximum biological capacity. Around 24% are over- exploited, depleted or recovering from depletion, while 21% are moderately exploited. Only 3% are underexploited.

The FSA is inviting industry bodies, environmental, health and consumer groups to provide their input.

Rosemary Hignett, head of the organisation's nutrition division, said: "We are aware that fish consumption and sustainability is a key issue for many consumers and current advice can be confusing."

FSA advice at the moment is that people should eat at least two portions of fish per week, one of which should be an oily fish such as salmon, mackerel or trout. Women who are pregnant, breastfeeding or want to get pregnant should not eat more than two portions of oily fish per week due to possible pollutants.

The decision to hold a review of the guidelines was last night welcomed by conservation charity, the WWF.

Sally Bailey, its programme manager for the north-east Atlantic, said: "We welcome this review of advice to consumers and look forward to the dialogue and consultation process. Obviously sustainability and health go hand-in-hand.

"Some of the fish stocks globally are in real crisis. UK cod is at an all-time low and it doesn't look good for the future. While there have been small increases in cod populations, we have to manage that.

"But it isn't simply a case of avoiding one type of fish in favour of another. It depends on a number of factors including how and where the fish is caught. For example, a lot of north-east cod stocks are overfished, but some cod stocks elsewhere are in a healthier stake."

Instead, Ms Bailey urged consumers to look for fish accredited with the Marine Stewardship Council (MSC) eco-label. The MSC is an independent non-profit organisation that promotes responsible fishing practices.

She added: "The MSC sets the criteria and doesn't have a vested interested - that's important. Looking for their label means consumers don't have to worry about what to buy."

James Simpson, spokesman for the MSC - which will participate in the review - said: "Interest in sustainable fishing has risen dramatically over the past couple of years and the FSA review reflects that. Around half of Scotland's fisheries are already at some stage of assessment in the MSC programme, demonstrating their commitment to working tow- ards certified sustainability."

The findings of the FSA's review are expected to be published by the end of the year.