FBI Director James Comey wasn't wrong when he said some in Poland were accomplices in the Holocaust, but his remarks -- which angered Poles and resulted in an apology Sunday night from America's top diplomat in Warsaw -- hit a raw nerve in a nation that suffered greatly at the hands of the Nazis, according to experts on the last century's darkest chapter.

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

- Stephen Mull, US ambassador to Poland

U.S. Ambassador Stephen Mull apologized for Comey's comments, in which the lawman told an audience at the U.S. Holocaust Memorial Museum, "In their minds, the murderers and accomplices of Germany, and Poland, and Hungary, and so many, many other places didn't do something evil. They convinced themselves it was the right thing to do, the thing they had to do." Mull, who was summoned to meet with Polish officials, emerged from the sit-down and made it clear Comey did not speak for the U.S.

" ... any suggestion that "Poland, or any other countries other than Nazi Germany, bear responsibility for the Holocaust, is a mistake, harmful and insulting," Mull said after attending ceremonies marking the 72nd anniversary of the Warsaw Ghetto uprising against the Nazis. "Nazi Germany alone bears responsibility.

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

Polish officials noted that 6 million Poles -- half of them Jews -- died at the hands of Nazis. Rabbi Abraham Cooper, associate dean of the Simon Wiesenthal Center, a global human rights organization researching the Holocaust, said he could understand the Poles' umbrage at Comey's remarks, even if they contained truth.

"Poland, the government and the Polish people, have often been upset when people say, in shorthand, 'Polish death camps, or 'Polish concentration camp,'" Cooper said. "What is very important to note is these camps were in occupied Poland. Many Poles took up arms against the Nazis, in the Warsaw uprising and before."

Cooper said the history of Jews in Poland, both before and during the Holocaust, is complicated.

"There are two interesting truths," Cooper said. "The largest number of righteous gentiles honored by Yad Vashem [Israel's Holocaust memorial] came from Poland. Having said that, it is also true that the level of anti-Semitism in Poland on the eve of the war was also extremely high."

The FBI did not return calls for comment.

Comey might not have been wrong in the literal sense, but his comments were "inartful," said Deborah Lipstadt, professor of Modern Jewish and Holocaust Studies at Emory University and author of the landmark 1993 book, "Denying the Holocaust: The Growing Assault on Truth and Memory."

"His heart was in the right place, but it was a very clumsy way of saying things," Lipstadt said. "Poland did not have its own government that it could be an ally or collaborator of Germany. If I were an advisor to Comey, I would have told him not to use Poland as an example.

"There were many people in Poland who certainly turned Jews in, and Poland was an anti-Semitic regime prior to the war. However, during the war Poland was an occupied country, unlike Hungary and France and others whose governments actively collaborated with the Nazis.”

President Obama caused similar outrage in 2012 when he referred to a Nazi facility in occupied Poland where Jews were processed for extermination as a "Polish death camp." Obama subsequently apologized.

Nazi Germany brutally occupied Poland from 1939-45, and ran death camps there, killing millions of Jews, Poles and others.

The Associated Press contributed to this report