Bartosz Cichocki said that Washington has been expressing "concerns and questions" about the law, but that reports of sanctions are untrue.
Polish news portal Onet.pl reported late Monday that the Polish government was told that the Polish president and prime minister cannot count on any meetings with either President Donald Trump or Vice President Mike Pence until Poland changes the law.
Onet said it has seen documents confirming the ultimatum, and reported that the Americans also threatened to block the financing of joint military projects.
The United States has previously warned Poland not to pass the law, which imposes prison sentences of up to three years for falsely and intentionally attributing the crimes of Nazi Germany to Poland.
Poland's nationalist government says the law is meant to protect Poland, a victim of Hitler's Germany, from being accused of crimes that it did not commit as a nation. Israeli and U.S. officials, however, fear that it could undermine free speech and academic research into the cases of Polish violence against Jews during World War II.
In late January the U.S. State Department said the law could have "repercussions ... on Poland's strategic interests and relationships."
"If it's true that Americans have introduced sanctions against Poland, then the matter is serious. It could hurt Poland's security," Stanislaw Tyszka, a deputy speaker of the parliament from a small right-wing party, Kuziz '15, said Tuesday.
Government spokeswoman Joanna Kopcinska stressed that diplomatic channels remain open, noting that other government officials have visited Washington recently and will do so in the near future.
"Bilateral strategic cooperation with the United States is not threatened, diplomatic contacts remain at the current level," Kopcinska said.
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