At the beginning of his cabinet's meeting in Zagreb on Thursday, Milanovic admitted that he had used perhaps "too strong language" during Question Time in parliament two days ago when opposition Croatian Democratic Union (HDZ) lawmakers raised the issue of ratification of the border agreement signed by Croatian and Bosnian presidents Franjo Tudjman and Alija Izetbegovic 13 years ago.

"Two days ago in parliament, I perhaps used too sharp rhetoric to get our political rivals to see reason and ratify the agreement which had been elaborated for ten years," the premier said.

"I appealed to their common sense and tried to persuade them to accept some arrangements and commitments ... but it seems that I was naive and made a mistake," he added.

He said he would reiterate his calls because "Croatia's interests are at stake".

As for his proposal during Question Time that the agreement should be ratified by a two-thirds majority, he said that he was again wrong.

He reiterated that in 2009 the HDZ-led government sent the proposal for the agreement's ratification to parliament including a condition that the document should be ratified by a simple majority, only to be against this proposal now.

Milanovic recalled that in 2009, the agreement won the support of three quarters of Croatia's lawmakers.

"We raised our hands because we deemed it useful for Croatia and we thought it provided people living along our 1000-kilometre-long border with Bosnia and Herzegovina with stability and security and predictability, which are the fundamental features of the rule of law," Milanovic said.

Commenting on his visit to Germany on Wednesday and his talks with Chancellor Angela Merkel and other German officials, Milanovic said the talks focused on matters of importance to Croatia, such as the ratification of the Croatia-EU accession treaty, the construction of the Peljesac bridge and economic issues.

He said that Croatia had been given guarantees that the Bundestag would ratify the accession treaty in a timely fashion.