A boy waves a Venezuelan national flag, as supporters of Venezuelan President Nicolas Maduro gather at Bolivar square in Caracas to take part in a signature campaign to urge the United States' to put a halt to intervention threats against Maduro's government, on February 6, 2019.

Venezuela's armed forces have barricaded a bridge on the country's western border with Colombia, in a dramatic attempt to prevent a delivery of humanitarian aid.

It comes at a time when tensions in Venezuela are reaching boiling point, with the South American country in the midst of the Western Hemisphere's worst humanitarian crisis in recent memory.

The opposition government, led by Juan Guaido, has said it is preparing to deliver tens of millions of dollars in food and medicine over the coming days, with supplies donated by the U.S. and others being stocked in warehouses near the border.

President Nicolas Maduro, who has the support of the military, has consistently rejected letting foreign aid into the country.

In a tweet on Wednesday, U.S. Secretary of State Mike Pompeo said: "The Maduro regime must let the aid reach the starving people."

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In addition to easing a devastating shortage of basic products in the crisis-stricken country, the opposition's proposed move to deliver aid is widely seen as an attempt to undermine Maduro's authority.

The socialist leader has long used subsidized food handouts as a tool to maintain the backing of his supporters.

"A delivery of humanitarian aid will test the loyalty of Venezuela's armed forces — this moment represents a tipping point," Diego Moya-Ocampos, principal political analyst for Latin America at IHS Markit, told CNBC via telephone.

"Food has been used as a political weapon to control the population and one of the many reasons Maduro has not allowed humanitarian aid into the country," he added.