Venezuelan doctors have called on the military to unblock the Tienditas International Bridge so humanitarian aid can reenter the country.
They protested on the Colombian side of the border to avoid repercussions at a time of huge political tension.
Opposition leader Juan Guaidó has proclaimed himself interim president after claiming Nicholas Maduro's presidency is illegitimate.
The US has imposed harsh sanctions on the country's oil exports.
Jens Laerke, a spokesman for the UN Office for the Coordination of Humanitarian Affairs, is committed to delivering aid.

Israel urges Lebanon to disarm Hezbollah under ceasefire terms
Russian attacks on Ukraine kill two
Kenya landslide death toll rises to 22
Fire at store in northwestern Mexico leaves at least 23 dead
