Warsaw (AFP) - The US ambassador to Warsaw apologised Sunday after being summoned by the foreign ministry over comments by the head of the FBI that Poland shared responsibility for the Holocaust with Germany.

Poland's President Bronislaw Komorowski said the comments in an opinion piece by FBI director James Comey were an "insult" to Poland.

"In their minds, the murderers and accomplices of Germany, and Poland, and Hungary, and so many, many other places didn't do something evil," Comey wrote in the April 16 Washington Post article.

After meeting with Poland's deputy foreign affairs minister, US ambassador Stephen Mull told reporters the Nazis bore sole responsibility for the Holocaust, which left six million European Jews dead in World War II.

"I made clear that the opinion that Poland is in any way responsible for the Holocaust is not the position of the United States," Mull said in Polish. "Nazi Germany alone bears responsibility."

"I now have a lot of work before me to make things right in this situation," he added.

Foreign ministry spokesman Marcin Wojciechowski wrote on Twitter Sunday that Mull would "receive a note of protest and a summons for an apology" over Comey's comments.

Komorowski told public television that the FBI head's comments showed a "lack of historical knowledge" and "this requires a reaction from the Polish state".

They were an "insult to thousands of Poles who helped Jews".

Mull was quick to offer an informal apology at memorial ceremonies in the Polish capital on Sunday marking the 72nd anniversary of the Warsaw Ghetto Uprising.

"Any suggestion that Poland, or any other countries other than Nazi Germany, bear responsibility for the Holocaust, is a mistake, harmful and insulting," Mull told reporters.

Six million Polish citizens were killed under Nazi Germany's occupation of Poland during World War II. While half of the victims were Jewish, the other half were Christian.

Historical records show instances of Poles turning against their Jewish neighbours, either killing them or giving them up to the Nazis. Poles also risked their lives and families to save Jews.

Story continues

In 2012, US President Barack Obama caused outrage in Warsaw when he labelled a World War II Nazi German facility in occupied Poland used to process Jews for extermination a "Polish death camp".

He subsequently expressed "regret".

Poland's government keenly watches the global media for descriptions of former Nazi German death camps as "Polish" because it says the term -- even if used simply as a geographical indicator -- can give the impression that Poland bore responsibility for the Holocaust.