Green MEPs say the commission's draft proposals on a nuclear waste directive contains "serious and alarming gaps."
EU energy commissioner Oettinger will unveil the commission's ideas for a directive on the management of spent fuel and radioactive waste on November 3.
But parliament's Greens/EFA group, which has seen a draft copy, says it fails to address "fundamental" issues, including the cost of dealing with spent nuclear waste "in 30 to 40 years' time."
Speaking at a breakfast briefing in parliament on Tuesday, group co-leader Rebecca Harms said the draft also fails to provide both an "accurate definition" of radioactive waste and a "true picture" of how each member state handles such waste.
Harms said such "glaring omissions" from the commission's proposals "give cause for real concern."
She cited the case of a salt mine where 126,000 barrels filled with radioactive waste will have to be retrieved from the salt mine Asse in Lower Saxony.
It is feared the unprecedented recovery of the waste from a depth of several hundred metres will cost billions of euros.
Harms said, "This shatters the illusion not only of salt as the ultimate, safe geology for radioactive waste but also for the reliability of geological assessments and, thus, for the long-term safety of nuclear waste repositories.
"In this case, it is so-called low and intermediate waste. What if high-level waste had been disposed of there?"
The German MEP presented a list of demands which she says the commission should meet to "help solve the dangerous waste problem."
One such demand, she told journalists, is for a ban on all shipments of spent nuclear fuel to reprocessing plants.
She said that any future directive on nuclear and radioactive waste should also cover uranium mining waste.
"The directive should also provide a clear framework for the decision-making process that member states should follow in the evaluation of all nuclear and radioactive waste management," said Harms.
"These are completely missing from the draft we have seen."
The Greens also criticised the commission's decision to use the so-called "written procedure" for publication of its proposals, saying this is "inadequate."
Harms said, "This issue is one of the most important facing the EU and we are calling for a systematic discussion before the commission goes for a regulation on this.
"This means an open, transparent and science-based debate."