EU plans for member states to accept 160,000 new asylum seekers represent a "drop in the ocean" in the scale of the crisis, Germany's vice-chancellor says.

Sigmar Gabriel said 450,000 people had arrived in Germany so far this year, with 37,000 in the first eight days of September.

Tens of thousands, mainly Syrians, have pushed north in recent weeks.

Serbian TV says a record 5,000 migrants have arrived at the border with Hungary in the past 24 hours.

The Hungarian army earlier started military exercises to prepare for a possible future role in guarding the border and stem the flow of people - a move criticised by human rights groups.

Meanwhile, Austria's government said 5,700 people had crossed over from Hungary in recent hours. National train operator OeBB temporarily suspended services from Hungary because of the increasing numbers and the risks of overcrowding.