Croatian PM Ivo Sanader said he hoped Slovenia would reconsider
Slovenia has moved to block neighbouring Croatia from joining it in the European Union, in a continuing dispute over boundaries.
Croatia began negotiations on joining the 27-member bloc three years ago, with further talks due on Friday.
But Slovenian Prime Minister Borut Pahor said Croatia had submitted maps showing boundaries Slovenia disputed as part of its pre-joining reform process.
Croatia denied the claim and called on Slovenia to reconsider its move.
Under EU procedure, a country needs to negotiate "chapters" to gain membership. Talks are firstly opened and then closed once an agreement is reached.
Croatia must complete 35 chapters, and had planned to open 10 and close five on Friday.
However, Mr Pahor said: "The Slovenian government agrees... to opening one chapter and closing three chapters."
He said Croatia was using documents in negotiations that are prejudicial to the 17-year-old territorial dispute between the two countries - a charge Croatia denies.
Croatian Prime Minister Ivo Sanader said his government still hoped to complete talks by the end of 2009 as planned and expected Slovenia to reconsider.
"I'm not a big optimist when I say that, but I think that it would be good if they did that," he said, according to AFP news agency.