LONDON (AP) — The U.S. ambassador to Britain has attacked what he described as a "smear" campaign against American agriculture by interests with a protectionist agenda.

Woody Johnson said in an article published in the Daily Telegraph on Saturday that U.S. food products are safe, and that scare stories about "chlorine-washed chicken" and "hormone-pumped beef" are being used to mislead the public. The comments come as Britain prepares to negotiate its own trade deals with the U.S. and other countries after Brexit.

Johnson says American producers use "scientific" and "technological" tools to feed a growing global population in contrast to the European Union's "Museum of Agriculture."

The U.K.'s National Farmers Union has raised concerns about U.S. practices, saying trade deals shouldn't allow imports produced "to lower standards than those required of British farmers."