Hungarian troops overnight began laying a razor-wire barrier along its border with Croatia to keep migrants out, Prime Minister Viktor Orban said Friday, following a similar move along the frontier with Serbia.

"During the night work already began on building the technical border closure... It seems we can rely on help from no-one," Orban said in an interview on public radio after thousands of migrants entered Croatia seeking to travel to northern Europe.

Croatia on Thursday closed seven of the country's eight border crossings with Serbia "until further notice" following a massive influx of migrants and refugees, the interior ministry said.

"Traffic is banned on the border crossings of Tovarnik, Ilok, Ilok 2, Principovac, Principovac 2, Batina and Erdut," the ministry said in a statement.

Several dozen migrants entered Croatia from Serbia early Wednesday, the first to enter the EU country after Hungary sealed its borders to thousand of people entering every day, an AFP correspondent saw.

The group of mostly Syrian or Afghan men, women and children crossed the border -- which was marked by nothing more than a stone -- early Wednesday morning and were picked up by police as they walked across a field.

A Croatian hostage whom the Islamic State group claims to have beheaded is thought to have been kidnapped by a criminal gang in Egypt before being turned over to the jihadists, Croatia's foreign minister said Thursday.

Tomislav Salopek, a 31-year-old father of two working for a French engineering company, was seized last month from a car some 22 kilometers (14 miles) west of Cairo.

The Islamic State group said Wednesday it has beheaded a Croatian hostage, and released a picture of a body after what would be the first such killing of a Westerner in Egypt.

Croatian Prime Minister Zoran Milanovic told reporters he could not "confirm with 100 percent certainty" that Tomislav Salopek, who worked for French company CGG, had been murdered.

Fears mounted Friday over the fate of a Croatian abducted near Cairo by Islamic State group militants who have threatened to execute him unless Muslim women in Egyptian jails are freed.

Croatian President Kolinda Grabar-Kitarovic said she would talk to her Egyptian counterpart Abdel Fattah al-Sisi by telephone as the 48-hour deadline set by the jihadists on Wednesday neared.

A Croatian working for a French company has been kidnapped in Cairo, the Croatian foreign ministry said Friday.

The 31-year-old man, identified only by his initials T.S. was abducted by gunmen on Wednesday when traveling to work in a car, the ministry said in a statement.

A Serbian war crimes suspect nicknamed "Captain Dragan" arrived in Zagreb on Thursday from Australia to face allegations of torture and murder after battling extradition for a decade.

"After a long battle, which started nine years ago, Dragan Vasiljković was extradited ... and is now in Croatia," Justice Minister Orsat Miljenić told reporters.

The U.N. Security Council was headed for a showdown Tuesday over a draft resolution that would formally recognize the Srebrenica massacre as genocide, after Russia threatened to use its veto.

As Bosnia prepares for somber national commemorations of the 20th anniversary on Saturday, the 15-member council was to vote on a text that condemns the killing of some 8,000 Muslim men and boys by Bosnian Serb forces in July 1995.

A play by best-selling French author Michel Houellebecq -- whose book imagining France under Islamic rule stirred controversy -- has been pulled from a Croatian arts festival due to security fears, organizers said on Thursday.

Houellebecq's drama "Elementary Particles" ("Les Particules elementaires") was to have been staged at this year's Dubrovnik Summer Festival.