Food aid in a warehouse on the frontlines of the Yemen war is at risk of rotting, the UN said Monday, leaving millions of Yemenis without access to life-saving sustenance. The Red Sea Mills silos, located in the western port city of Hodeida, are believed to contain enough grain to feed several million people for a month. But the granary has remained off-limits to aid organizations for months. "The World Food Programme (WFP) grain stored in the mills -- enough to feed 3.7 million people for a month -- has been inaccessible for over five months and is at risk of rotting," read a joint statement by the UN aid chief and special envoy for Yemen. Hodeida, and its food silos, have been in the hands of Yemen's Houthi rebels since 2014. UN aid chief Mark Lowcock on Monday said the rebels had made "efforts to re-open the road leading to the mills". On Thursday, Lowcock issued a public plea to the Huthis to allow relief groups to cross front lines to reach the Red Sea Mills, warning the remaining grain could spoil. A joint statement between Griffiths and UN aid chief Mark Lowcock said the UN was scaling up its operations to provide food assistance to nearly 12 million people across Yemen struggling to meet their daily food needs. Accessing the 51,000 tonnes of UN wheat and milling equipment at the frontline flashpoint is a key aim of ongoing peace talks. — Agencies