As the plot thickens in the UK horsemeat food fiasco we answer five questions on the latest developments.

What’s happened now?

Due to more products being found to contain horsemeat – the latest is Findus’s lasagne containing up to 100 per cent horsemeat – The Food Standards agency has ordered all UK retailers to test processed beef products for horsemeat.

The agency has asked for test results by next Friday.

Findus had tested 18 of its beef lasagne products and found 11 meals containing between 60 per cent and 100 per cent horsemeat. The products were made by a third-party French supplier, Comigel, who alerted the company that they may not “confirm to specification”.

Why is this happening?

No one knows for sure, but there has been speculation that criminal activity may be responsible.

The Food Standards Agency (FSA) has already said it was "highly likely" criminal activity was to blame for the contamination.

It’s Chief executive Catherine Brown told the BBC: "I have to say that the two cases of gross contamination that we see here indicates that it is highly likely there has been criminal and fraudulent activity involved.”

The FSA added that police are involved in ongoing enquires in relation to the horsemeat scandal.

Is there any health risk from all this unauthorised meat that has found its ways into supermarkets’ frozen foods?

No. The FSA has said:

"There is no reason to suspect that there's any health issue with frozen food in general, and we wouldn't advise people to stop eating it."

Although, it has asked Findus to test its products for the veterinary drug phenylbutazone, or "bute, which is not allowed to the enter food system, but if it did it could be harmful to humans.

Is this food still on supermarket shelves?

On Monday Findus withdrew its beef lasagne in 320g, 360g and 500g sizes as a precaution

Earlier this week, Comigel had advised Findus and Aldi to withdraw Findus Beef Lasagne and Aldi's Today's Special Frozen Beef Lasagne and Today's Special Frozen Spaghetti Bolognese. An Aldi spokesperson confirmed they had been removed and it is conducting its own investigation.

Tesco also decided to withdraw Everyday Value Spaghetti Bolognese as it was produced at the same site, but there is no evidence it has been contaminated.

What’s going to happen next?

Most likely more revelations, these are expected as further testing is carried out.

Labour's Mary Creagh told the BBC:

"What we have had over the last four weeks is a constant drip, drip, drip of revelations from the food industry, from the Food Standards Agency, and what I am worried about is that the more they are testing for horse, the more they are finding," she said.

Adding: "It's simply not good enough for ministers to sit at their desks and pretend this isn't happening."

A statement from the British Meat Processors Association (BMPA) to the BBC said "deplores the latest reported incidents of gross contamination of some processed meat products".

"The BMPA has urged its members to be vigilant, and to review their raw material and ingredients-sourcing procedures in order to ensure that they meet their responsibilities to produce safe food and to describe and label their products accurately."