Oracle and Sun are both competitors in the global database market.
Neelie Kroes, the European commissioner for antitrust issues, said regulators would "very carefully examine" the deal that has approval from Sun shareholders and the U.S. Justice Department, The New York Times reported Thursday.
The deal was proposed in April. Oracle, the world's second largest software producer, approached Sun with intent to capture Sun's MySQL open-source database and Java software, the Times said.
Both are California companies. But the European regulators said Sun's "open source nature … might not eliminate fully the potential for anti-competitive effects."
Open-source refers to software development that is, in effect, public with an open or shared source code.