Venezuelans petition Obama ahead of summit

The Venezuelan president, Nicolas Maduro, says he is taking a petition for President Obama containing the signatures of 10 million Venezuelans to the Summit of the Americas in Panama.

The petition demands that the United States withdraws sanctions it imposed on a group of Venezuelan officials three weeks ago.

The US has accused the officials of human rights abuses against President Maduro's opponents.

The BBC's Ian Pannell is in Caracas, where there have been widespread shortages of some basic goods and queues have become a familiar sight around the city.