Bickering between Balkan rivals Serbia and Croatia over a migrant surge has turned personal, with Croatia's prime minister saying he no longer wants to speak with his Serbian counterpart.

The two former Yugoslav nations, which were at war in the 1990s, imposed tit-for-tat border regulations last week, but the dispute appeared to have eased on Friday.

Croatia has been accusing Serbia of sending thousands of migrants to its border, instead of channeling them up north to Hungary.

On Monday, Croatian Prime Minister Zoran Milanovic said he no longer wanted to speak to Serbian counterpart Aleksandar Vucic over the issue, while Vucic said he would "speak to the devil" to restore regional stability.

Croatia said Monday that 78,000 migrants have crossed its border from Serbia in the past 12 days.