The United Nations should withdraw all its personnel from Afghanistan as the country has become too dangerous to work in, the UN staff union has said. The union said staff should leave the country until new security measures had been introduced. The union said UN personnel was likely to become a target in the run-up to October's elections. "As we approach election time, more than likely attacks will intensify," union vice-president Guy Candusso said. **Baghdad bomb*** The union's call came days after a series of bombs exploded at a voter registration centre in western Afghanistan, near the border with Iraq. Thursday marked the one-year anniversary of attacks on the UN's headquarters in Baghdad which left 22 dead, including envoy Sergio Vieira de Mello. UN Secretary General Kofi Annan has said the organisation is wrestling with the difficult question of how to remain involved in areas where they are increasingly under attack. "How do we operate in places like Iraq and some parts of Afghanistan, where many people want and expect us to help... but some are determined to block our work at any price?" he said on Thursday. In July global medical aid group Medecins Sans Frontieres (MSF) announced it was leaving the country after 24 years, citing security fears. **PHOTO CAPTION*** A worker stands on top of the dome of the Abdul-Rahman's mosque under construction in the center of Kabul, Afghanistan, on Saturday, Aug. 21, 2004. (AP)