An increasing number of migrants is amassing at Greece's eastern border, abetted by neighboring Turkey, which provides buses to transport them to the area and has left its own border open.

Overnight tension continued, with some migrant throwing rocks at Greek police and the latter replying with tear gas and stun grenades.

While many migrants have congregated at the two official entry points _ both shuttered on the Greek side _ some are searching for passages along the river Evros, which forms almost all the land border between Greece and Turkey. With rain having been scarce lately, the river is shallow at m any points.

More police and army forces are being sent from the region of Central Macedonia; two special forces units are already operating at the border area.