The U.N. human rights office is expressing concern about deteriorating human rights, growing violence and "severe shortages" of food, medicine and basic goods in Venezuela.

The office of human rights chief Zeid Ra'ad al-Hussein points to reports of rising protests demanding access to food, the arrest of hundreds of demonstrators and excessive use of force against protesters in recent weeks.

The Geneva-based office on Tuesday urged Venezuelan authorities to ensure the right to freedom of expression and peaceful assembly and "to consider accepting humanitarian aid" to ensure food and medicine supplies are distributed.

Venezuela's government opened its long-closed border with Colombia over the weekend, prompting more than 100,000 Venezuelans to cross to buy as many basic goods as possible amid an economic crisis and 700-percent inflation in Venezuela.