The EU's executive commission is poised to give Bulgaria and Romania warnings that their reforms to join the bloc in 2007 have fallen behind schedule, enlargement commissioner Olli Rehn said Thursday.

The "early warning letters" to be dispatched to Sofia and Bucharest "will focus on the evident current shortcomings in the reforms of both countries", he told reporters.

"This effectively means a yellow card," he said, adding, "I trust that both countries can read the political climate of Europe so that they take these yellow cards particularly seriously so as to avoid the use of the safeguard clauses," which could delay accession a year.

The European Union is facing a growing political crisis after French and Dutch voters rejected the bloc's first-ever constitution in referendums partly because of concerns enlargement is going too far and too fast.

The commisioner said that the warnings pointed out five areas where Bulgaria has fallen behind and seven for Romania.

In particular, Bularia needed to reform its legal system to ensure greater independence among judges and fight corruption.

"Bulgaria has still plenty of homework to do ... Bulgaria must understand that it is not off the hook but it still has to do its homework", he said.

Romania also needed to reform its legal system as well as its police forces and fight against corruption.