By Sarah Mortimer LONDON, Feb 11 (Reuters) - Restrictions on a government-backed pension plan aimed at helping more Britons save for their retirement should be lifted as a matter of urgency, a parliamentary committee said in a report on Monday. The Work and Pensions Committee said removing the limitations on the National Employment Savings Trust (NEST), which cap the amount an employee can contribute to their pension pot each year and ban transferring existing pensions in and out of the scheme, should not be delayed until 2017.