BRUSSELS, August 4, 2008 (AFP) - Belgian mussels have been pulled from the market due to toxic contamination, the country's food agency has announced, obliging lovers of the national dish 'moules-frites' to rely solely on foreign shellfish.

The measure was taken after algal toxins that may cause Diarrhetic Shellfish Poisoning (DSP) in humans were detected in an early batch of the summer crop.

For lovers of mussels and chips -- the iconic 'moules-frites' -- the news is not too much of a blow as the local input to the market is small, with just two Belgian producers, SDVO and Reynaert-Versluys.

The main ingredient for Belgian's national dish is imported largely from the neighbouring Netherlands.

Dutch producers are looking this year to bring 40,000 tonnes of the bivalves to market, compared to just 15 tonnes of Belgian North Sea mussels expected this summer.

The first mussels to reach the Belgian market on July 17 were feted with the traditional celebrations.

However after the first Belgian mussels of the season were sold at the port of Ostend last month, official tests detected the presence of the toxic algae responsible for gastric problems.

The Belgian market will not be reopened until further tests for the toxin prove negative, Belgium's Federal Agency for the Safety of the Food Chain said Monday.

'People who have consumed Belgian mussels and who suffer these symptoms should contact their doctor,' the agency warned over the weekend.

Those still in possession of Belgian mussels were advised to take them back to where they bought them for a refund.