(Adds CRA statement)By Maximilian HeathBUENOS AIRES, Dec 30 (Reuters) - Argentina will suspend sales of corn for export until Feb. 28, the agriculture ministry said on Wednesday, announcing the surprise move as part of the government's effort to ensure ample domestic food supplies.The move by the world's No. 3 corn supplier was a sign of tightening global food supplies during the COVID-19 pandemic.