Britain is hugely unprepared for the potential impact of Brexit on environmental protection, with more than 1,100 pieces of EU green legislation needing to be moved into UK law for safeguards to be maintained, according to a report by the Green MP Caroline Lucas.

Lucas, who spent 11 years as an MEP before being elected to parliament, said environmental protections faced “a cocktail of threats from Brexit”.

This was in part, Lucas argued, because the government might seek to water down some rules as it transposes them to UK law. But the risks are also structural, she said, with the possibility of less spending on environmental protections and a loss of cross-border cooperation.

Lucas, the Brighton Pavilion MP, has called for a so-called green guarantee over Brexit – a government promise that protections will not be reduced, and the issue would not be ignored amid a focus on areas such as trade deals.

The 35-page report details House of Commons Library research which has identified more than 1,100 EU environmental laws which will need to be moved to UK legislation. The government has not even fully identified all such laws needing attention, Lucas said.

The report identifies a series of ways in which environmental oversight and protection could suffer. One areas is enforcement – Lucas notes there is no UK equivalent for the European Commission and European Court of Justice in terms of acting over breaches of environmental legislation.

Brexit will also mean the UK leaving regulatory organisations such as the European Environment Agency and the EU’s Chemicals Agency, as well as the Emissions Trading Scheme.

Lucas also cites the concern, raised by others, that a rush to agree a free trade deal with the US could see Britain obliged to accept imports of food involving practices not allowed in the EU, for example chicken rinsed with chlorine and beef from hormone-treated cows.

The report also says the government will have to step in to cover funding in areas connected to environmental protection if it wants the scheme to continue, for example, major EU grants for green farming practices.

Lucas said the report, published shortly after the bill allowing the government to trigger article 50 and thus start the formal Brexit process was approved by the Commons, showed that the UK was about to enter a period of “profound uncertainty” over environmental protections.

“Outside the EU, there will be much greater probability of legislative change in the UK, more exposure to the political cycle and a danger that investors will be wary of potentially higher risks,” she said. “The relative attractiveness of the UK as a place for green investment is in danger of being further reduced.”

She added: “Theresa May’s courting of the United States in pursuit of a new free trade agreement poses an even greater risk that ministers may be tempted to water down regulations - such as those on GMOs, pesticides, and animal hormones. We could see chlorinated chickens and hormone beef on UK markets.”