FTSE 250-listed Ultra Electronics warned that revenue for 2013 would be slightly below the previous year's, hit by 'a number of headwinds', in particular the US government-funded market. Overall, its performance is expected to be broadly in line with expectations. In the US government-funded market, the unexpected shut-down in October further affected the federal procurement process, delaying expected orders, approvals and payments, Ultra said. The prolongation of the group's Oman contract continued, with further delays in accessing buildings. As a result, Ultra's installation phase has now been deferred from the fourth quarter of 2013 until next year. The group continued: "Ultra's management continues to focus on efficient contract delivery and cost control, using the mechanisms put in place in January, to respond to market conditions. "Ultra continues to identify and position for a number of larger opportunities that will generate medium term revenue growth. Some good progress has been made since August. "The group is well placed for the future with its proven business model, programme positions and medium term growth opportunities."The company reported that its balance sheet remained strong and said it had "substantial headroom" on its current banking facilities. NR