CARACAS - Venezuela on Tuesday was set to expel a crew of Al Jazeera journalists who were intending to cover an opposition march against President Nicolas Maduro, the country’s union of journalists said. With Venezuela in the throes of severe economic and political crises, the opposition has called for a march on Caracas on Thursday to press its constitutionally sanctioned demand for a referendum to remove Maduro. The authorities detained three employees of the Qatar-based channel when they arrived Monday at Maiquetia international airport outside Caracas, the National Union of Press Workers (SNTP) said on Twitter.