Around 1,500 migrants tried to enter the EU member state illegally from Serbia this month, with 500 alone caught between Friday and Sunday, police said in a statement.
Many were economic migrants from Morocco, Iran, and Pakistan, police said. Unlike Syrians, they are unlikely to be granted asylum in Europe and face deportation.
About 300,000 migrants and refugees passed through Hungary last year, before right-wing Hungarian Prime Minister, Viktor Orban, sealed off the southern borders with razor wire and fences in September and October.
The measures --together with tight border patrols and tough new laws punishing illegal entry and vandalism of the fences-- slowed the flow to a trickle with only around a dozen people a day attempting to cross.
Since September, 1,325 people have been charged with crimes under the new legislation, the vast majority served with expulsion orders.
There are fears that a newly introduced daily cap on asylum-seekers in neighbouring Austria could trigger a domino effect along the Balkan migrant trail and leave thousands stranded in Greece, the entry point into the EU for many.
In 2015, more than a million migrants reached Europe -- nearly half fleeing the five-year-old Syrian war.
Austria last year took in 90,000 asylum seekers, making it one of the highest recipients in the EU on a per-capita basis, while almost 10 times that number passed through, mostly to Germany and Sweden.
Faced with a resurgent far-right opposition topping opinion polls, Austria announced last week it would only accept 80 asylum claims a day and allow a maximum of 3,200 migrants to transit the country.
In response, Slovenia, Serbia, and Croatia have also tightened their borders.
Hungary has warned that it was ready to quickly build a fence on the Romanian frontier if migrants begin moving in that direction.
Editor: Ade P Marboen
Copyright © ANTARA 2016
