FRANKFURT (Reuters) -Bayer has warned U.S. lawmakers it could stop selling the popular Roundup weedkiller if they cannot provide better legal protection against product liability litigation, according to a financial analyst and a person familiar with the matter.

Bayer has already paid about $10 billion to settle disputed claims that Roundup, based on the glyphosate herbicide, causes cancer. There is a backlog of about 67,000 pending cases for which the group has set aside a further $5.9 billion in legal provisions.

"Without regulatory clarity (Bayer) will need to exit the business. Bayer have been clear with legislators and farmer groups on this," analysts at brokerage Jefferies said in a note on Thursday, citing guidance Bayer's leadership provided in a meeting.

Disclosing glyphosate sales numbers for the first time, Bayer on Wednesday said the product, one of the most widely used weedkillers in U.S. field farming, generated 2.6 billion euros ($2.8 billion) in revenue last year.

"Bayer could reach a point in the future where the company is forced to discontinue the sale of the product in the United States," a person familiar with the matter told Reuters.

Bayer, which acquired the product under the $63 billion takeover of Monsanto in 2018, said: "We are exploring every possibility to end this litigation" and declined to comment further.

(Editing by Gerry Doyle)