The attempt came a week after 60-70 people tried to get into Hungary at another Serbian border crossing under cover of night, prompting security staff to fire warning shots in the air.

Hungarian police report a sharp rise in attempts to cross the country's southern borders since December.

"The Tompa road border-crossing has been temporarily closed... as undisturbed crossing cannot be guaranteed due to a large group of migrants near the Serbian side," said a statement on the police website Thursday.

A Serbian border police officer confirmed to AFP that "about a hundred migrants" were on a strip of land between Serbia and Hungary, demanding that Hungarian authorities allow them in.

He added they were peaceful, and declining to give details on how they had reached the border area.

"We are peacefully protesting. We want to be allowed to continue our journey toward western Europe," one man told the HVG.hu news site.

Some of those in the group said they were from Syria, Afghanistan and Yemen and that they would stay in the area between the two borders until they were let through.

Placards held by some migrants read "We are just refugees, not criminals" and "Let us cross".

Later on Thursday Serbian public broadcaster RTS showed images of migrants, including women and children, sitting or lying in sleeping bags. RTS reported that there were a few hundred migrants.

Serbia's Defence Minister Aleksandar Vulin was on his way to the border, the RTS reported, giving no further details.

An advisor to nationalist Hungarian Prime Minister Viktor Orban said last week that more than 3,400 attempts were made last month alone to cross the country's southern borders, compared with several hundred a month last year.