What are the questions that the Government is trying to answer now?

The Government is still trying to find out how the lethal avian flu strain H5N1 arrived at the Bernard Matthews plant in Holton, Suffolk, and how turkey chicks on the adjoining farm became infected – 160,000 birds were gassed last week.

The company has admitted importing turkey carcasses from Hungary and sending meat back to that country for further processing. So far, however, there has been no formal link established between Bernard Matthews and the two farms in the Csongrad region of Hungary. The main clue is that turkeys slaughtered at an abattoir in Kecskemet, just outside the Hungarian exclusion zone, were imported to the UK.

Hungarian poultry chiefs and state vets are now trying to find out if there is any link between the abattoir and the infected farm and whether there have been any movements of people or vehicles from the infected zone to the abattoir.

Vets are working on the theory that turkey chicks in UK were infected by wild birds or rats who had picked up the deadly virus from uncovered poultry waste at the plant.

Meanwhile the Food Standards Agency is trying to find out if any infected meat has ended up on supermarket shelves.

Is there any sign that the virus has got beyond the confines of the Bernard Matthews farm in Suffolk?

For the moment there is no evidence that the virus has escaped to other farms in the area, or that it has infected wild birds. The Government and wildlife groups have stepped up testing of wild birds since the avian flu outbreak 10 days ago and still not one bird has been found with the disease.

It seems there is a possibility that the virus has travelled in meat or partly-processed meat products. Has this happened before?

There has been evidence of the virus spreading through movements in the poultry industry outside Europe, but this is the first suspect case in the UK and in the EU where the virus has spread through trade links - although the precise route is still unclear.

What are the implications if infected meat is shown to have entered the food chain? Are there rules to regulate this?

If infected meat has entered the food chain and has come from an infected zone where trade is banned, such as the Csongrad area of Hungary, the goods are deemed illegal and will be recalled. Supermarkets are on standby awaiting orders for a recall, but so far the Food Standards Agency has not identified such a trail in the food chain. The FSA has made clear that throughly-cooked infected meat causes no problems for human health.

Sir David King, the Government chief scientific adviser, has raised concerns that waste from any infected meat may contaminate the wild bird population in the UK. A recall to prevent this infection of wild birds was considered, but discounted by experts as a disproportionate response, especially as infected meat does not harm humans if cooked properly. It seems likely, however, that if it is revealed that infected turkey is on the market, consumers will reject it and refuse to buy the products.

The Bernard Matthews operation seems very complicated. Is it typical of the international poultry trade?

The Bernard Matthews operation is a complex one. He sends hatching eggs to Hungary where the chicks are fattened up on farms. Feed and labour is cheaper in Hungary than in UK. The birds are then slaughtered at the company plant in Sarvar or at the Kecskemet abattoir and the carcasses are transported to the UK. The breast meat from the birds is extracted at the Holton plan tin Suffolk and the rest of the meat is despatched back to Hungary for use in the production of turkey sausages which are then sold in Hungary, Germany and Italy. All this trade is legal and regulated and as it is within the EU is regarded as normal cross border trade. Even the trade between the two countries since the outbreak is lawful and within EU regulations. Bernard Matthews, however, suspended trade between the plants last Thursday when government epidemiologists confirmed the virus found in Hungary and in Suffolk was an identical strain.

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