Only £168 million, of the £1.5 billion pot, had been paid out by March 2012, rather than the expected £500 million.
By the end of March this year, some £577 million had been paid out to 407,000 policyholders, with a further 664,200 payments totalling £370 million due to be made by the time the scheme winds up in March 2014.
The committee has urged ministers, and the Government agency National Savings & Investment (NS&I) which operates the scheme, to bring forward the publicity campaign, the cross-party committee said it was "concerned" that some policyholders will miss out.
NS&I estimates it has already gone £4 million over budget.
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