The UK government has denied claims it ignored warnings that horsemeat slaughtered in the UK and destined for export to Europe could contain veterinary drug phenylbutazone.

According to reports over the weekend, the UK's food standards watchdog was warned in 2011 that the horse passport system - designed to control horses entering the food chain - could potentially allow horses treated with the drug, also known as bute, to be slaughtered for meat. Sources suggested the Food Standards Agency and the Department for Environment, Food and Rural Affairs failed to take appropriate action to guard against the eventuality.

However, following an investigation launched by Environment Secretary Owen Paterson, Defra insisted the warnings were treated appropriately at the time.

"The Secretary of State asked the chief executive of the FSA and Defra officials to look into allegations that information about horse passports had not been investigated. From those investigations, it's clear that Defra and the FSA have taken action on the issue of potential falsifying of horse passports, including individual enforcement action when information has been passed to us," a spokesperson for Defra told just-food. "In January 2012 Defra and the FSA increased checks on horse passports, meaning every horse was checked twice."

Following recent confirmation that bute was in a proportion of UK horsemeat, the authorities moved to further step up checks, the spokesperson added. "From last week no horse can enter the food chain until it is confirmed to be free of bute."

The news comes as the European food industry is rocked by a scandal involving the presence of horsemeat in beef products. The spokesperson emphasised these issues were unrelated.

"The issues surrounding falsified horse passports are unrelated to the fact that horse meat has been fraudulently passed off as beef in a number of products," the spokesperson said.

Paterson is today meeting with businesses to find out "what they are doing to restore the confidence of consumers", the spokesperson added.