BEIRUT (REUTERS) - The Islamic State militant group has seized Syria's last border crossing with Iraq after Syrian government forces withdrew, the Syrian Observatory for Human Rights monitoring group said on Thursday.

The al-Tanf crossing, known as al-Waleed in Iraq, is in Syria's Homs province, where Islamic State on Wednesday seized the historic city of Palmyra from government forces.

An Islamic State in Iraq and Syria fighter contacted by Reuters confirmed the group had taken control of the crossing, which is a 240km drive from Palmyra.