German Foreign Minister Frank-Walter Steinmeier said that EU members reluctant to accept migrant quotas may have to be outvoted and overruled in the 28-member bloc.
Hungary plans to build a fence to keep migrants out along part of its border with Romania in addition to the barrier being erected along the frontier with Serbia.
Hungary's populist prime minister called for a massive aid package to be given to countries around war-wracked Syria to help stem the flow of migrants to Europe.
President Barack Obama has asked for at least 10,000 Syrian refugees to be admitted to the United States next year, amid criticism his government has done too little to help.
Around 450,000 refugees have arrived in Germany so far this year, including 37,000 in the first eight days of September, Vice Chancellor Sigmar Gabriel told parliament.
EU president Donald Tusk urged a crackdown on the "murderers" among human traffickers who have killed scores of people trying to reach Europe from conflicts abroad.
Australia's hardline policy on asylum-seekers is under pressure as public sympathy for Syrians escaping conflict swells in a nation built on migration.
The Greek island of Lesbos is "on the verge of explosion" with violence erupting as the more than 15,000 mainly Syrian refugees push local resources to the limit.
Prime Minister Benjamin Netanyahu said he would not allow Israel to be "submerged" by refugees after calls for the Jewish state to take in those fleeing Syria's war.
Germany readied for hundreds more refugees to arrive from Hungary via Austria, a day after thousands were greeted, often by volunteers holding signs that read "Welcome to Germany".
Britain promised to take in thousands more Syrian refugees and give 100 million pounds in extra aid, as their plight raised pressure on European leaders.
Kazakhstan has accepted five former Guantanamo prisoners seeking asylum in the country. United Nations High Commissioner for Refugees has praised the move.
An Israeli shelling on a UN school in Gaza killed 20 people early Wednesday, medics said, as Palestinian factions were to head to Cairo to discuss a temporary humanitarian ceasefire.