The United Nations on Tuesday called for an independent investigation into the deaths of at least 23 people after about 2,000 migrants tried to cross from Morocco into Spain last week. The UN rights office voiced alarm at the deaths and dozens of injuries after migrants tried to storm the heavily fortified border between the Moroccan region of Nador and the Spanish enclave of Melilla on Friday. “We call on the two countries to ensure an effective and independent investigation is held as a first step towards establishing the circumstances of the deaths and injuries,” the office’s spokeswoman Ra…