Far-right extremists have attacked asylum seekers stranded at the Keleti train station in the Hungarian capital Budapest and on the Greek island of Kos.
Many of the refugees at the Keleti station formed human chains on Friday to protect women and children against the extremists throwing fire crackers and bottles. Police forces interfered later to maintain order.
Earlier in the day, a group of "thugs" with bats attacked asylum seekers on the island of Kos, telling them to "go back to their countries," rights group Amnesty International said in a statement. Some 15 to 25 people launched "a violent attack on refugees," the statement said, adding that riot police fired teargas to disperse the crowd.
Europe is facing an unprecedented influx of refugees, mainly coming from conflict-stricken countries like Syria, Iraq, and Afghanistan. Most of the refugees land in Italy or Greece, and then head for the wealthier countries of northern Europe by transiting through countries in Eastern Europe and the Balkans, like Macedonia, Serbia, and Hungary.
Nearly 340,000 asylum seekers reached the borders of the European Union during the first seven months of the year, up from 123,500 during the same period in 2014, according to the bloc's border agency Frontex.
Late on Friday, Hungary said it would send some 100 buses to take thousands of refugees who are walking towards the border with Austria.
"During the night, buses will be brought to Keleti train station and to the M1 motorway where transport to the Hegyeshalom border crossing will be offered to the migrants," Hungarian Prime Minister Viktor Orban's Chief of Staff Janos Lazar told a press conference.
Meanwhile, the mayor of the Greek island of Lesbos, Spyros Galinos, called for "immediate measures" to help alleviate the acute refugee crisis on the island, the entry point for hundreds of thousands of asylum seekers arriving in Greece.
"I appeal to [Greek] Prime Minister [Alexis Tsipras] for immediate measures," he told state television on Friday, describing the situation as a bomb about to explode in his hands.
Earlier on Friday, clashes erupted between police and some 1,000 people, mainly Afghans, who tried to rush onto a ferry heading to Greece's main port of Piraeus, near the capital Athens. Police used stun grenades to drive back the crowd.