Sofia on Friday said it takes serious note of the European Union's written warnings to Bulgaria and Romania that they are behind schedule on reforms needed in order to join the EU in 2007.

"Such letters are standard practice, but we need to take them seriously and pay attention," Bulgarian foreign ministry spokeswoman Guergana Grancharova told AFP.

"What matters in the months ahead, is that Bulgaria stays on course and continues implementing the reforms without wasting a single minute," she said.

EU enlargement commissioner Olli Rehn said Thursday in Brussels that the Union would send early warning letters to Sofia and Bucharest to point out "evident current shortcomings" in efforts to bring the countries up to EU standards.

The two countries both have "safeguard clauses" in their accession treaties that will kick in if their reforms fail to satisfy Brussels and that could delay accession until 2008.

"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," Rehn said.

He urged Sofia to take special care to ensure the independence of its judiciary and to combat corruption.

Bulgaria's European Integration Minister Meglena Kouneva on Friday told the Troud newspaper that Sofia expected the EU warning would also focus on agriculture, the environment, the provision of services and the protection of intellectual property rights.