Kroes ignited a firestorm of criticism last week when she was quoted as saying state aid could be cut in the poor regions of some countries that are not among the 10 new members, which could affect Germany and Italy. Her testimony was different.
"We must ... guarantee that there is no discrimination between otherwise similar regions just because they happen to be situated in different member states," Kroes told the European Parliament's monetary and economic affairs committee.
That was insufficient for Committee Chairwoman Pervenche Beres, a French socialist, accusing Kroes of a free market agenda.
"It's not a strategy, it's an ideological position," Beres told reporters of Kroes' presentation. "There will be much discussion on the state aid issue."
Kroes' testimony echoed the views of the full Commission, which were unveiled one day earlier by President Jose Manuel Barroso as part of a revised Lisbon agenda for European growth.
Kroes reaffirmed earlier promises to investigate "a limited number of key sectors where competition does not appear to be functioning as well as it might".
She cited the transport, energy and financial services sectors but added she had no proof of wrongdoing.