The European commission has rejected calls from eastern Europe to introduce a so-called double genocide law that would criminalise the denial of crimes perpetrated by communist regimes, in the same way many EU countries ban the denial of the Holocaust.

Last week six countries wrote to Viviane Reding, the European justice commissioner, calling for the "public condoning, denial and gross trivialisation of totalitarian crimes" to be punished.

Foreign ministers from Lithuania, Latvia, Bulgaria, Hungary, Romania and the Czech Republic said communist crimes "should be treated according to the same standards" as those of Nazi regimes, notably in those countries with Holocaust denial laws.

But the EU executive will say in a report due tomorrow that opinion is too divided on the matter and that there is no legal basis allowing Brussels to act.

"There is no consensus on it. The different member states have wildly differing approaches," EU justice spokesman Matthew Newman told the Guardian. He said the commission takes the issue "very seriously", but: "At this stage, the conditions to make a legislative proposal have not been met. The commission will continue to keep this matter under review."

The east European countries point to the EU's ability to make laws relating to "particularly serious" cross-border crimes and a separate EU decision permitting the crafting of rules targeting racism and xenophobia.

But the commission says neither legal instrument mentions totalitarianism and rejects the idea of double genocide. "The bottom line is, obviously, what they did was horrendous, but communist regimes did not target ethnic minorities," said Newman.

According to Lithuania, whose foreign minister leads the campaign to create a new law, the EU's understanding of genocide should be extended to include crimes against groups defined by "social status or political convictions".

Andrius Grikienis, a spokesman for Lithuania's mission to the EU, said: "During the first years of Soviet occupation, Lithuania lost more than 780,000 of its residents. 444,000 fled Lithuania or were repatriated, 275,697 were deported to the gulag or exile, 21,556 resistance fighters and their supporters were killed and 25,000 died on the front."

By comparison, he said: "More than 200,000 citizens of Jewish origin were killed by Nazis and their collaborators."

The commission is also uneasy about wading into a highly controversial area. A number of western EU countries oppose the proposal, suggesting that it is a thinly-veiled attempt at rehabilitation of domestic collaborators while antisemitism remains a live issue on the streets and in the media in the east.

On 25 November, the ambassadors to the Lithuanian capital, Vilnius, of seven EU states including the UK sent a letter to the country's president complaining about a newspaper article by an interior ministry historian, Petras Stankeras, that described the Holocaust as a "legend".

In the letter, they complained about how a court in May had ruled that the swastika is a "traditional Lithuanian symbol" while "spurious attempts are made to equate the uniquely evil genocide of the Jews with Soviet crimes against Lithuania, which, though great in magnitude, cannot be regarded as equivalent in either their intention or result".

Efraim Zuroff, the Nazi-hunter and director of the Simon Wiesenthal Centre's Israel office, describes the effort by the six eastern states as a "false symmetry".

"We have no problem with a day of commemoration for communist crimes, and indeed, something should be done, but the Holocaust was a unique tragedy in history," he said.

"For all the terrible crimes of the USSR, you can't compare the people who built Auschwitz with the people who liberated it. Nazi Germany would probably not have been defeated if it weren't for Russia."