The European Commission has begun legal action against 24 European Union countries over their failure to transpose new securities trading rules into national law on time.
Only Ireland, Britain and Romania transposed the Markets in Financial Instruments Directive (MiFID) into national law by January 31st, a commission spokesman said.
MiFID forms the cornerstone of the EU's single financial market and is seen as key to boosting competition in share and bond trading to cut costs for investors and make the economy more efficient.
The rules are due to come into effect in November but there could be legal uncertainty if some countries are late.
EU Internal Market Commissioner Charlie McCreevy sent the 24 countries two letters. The first urged them to make the introduction of MiFID a political priority, while the second started a three-stage legal action that could end at the European Court of Justice, the bloc's top court.
"Further delays in implementation of national legislation will give firms less time to prepare for a completely new regulatory environment," Mr McCreevy said in a statement.
Unless all EU countries introduce the new rules on time, there could be legal uncertainty for cross-border firms. "In this situation there is a risk that member states could face legal action by private parties who might claim damages for losses incurred because of late implementation of national legislation," Mr McCreevy said.