Home Secretary Jacqui Smith says she does not know when an inquiry will end into the bugging of a Labour MP visiting a constituent in jail.
Labour MP Sadiq Khan had welcomed the inquiry.
Justice Secretary Jack Straw told MPs on 4 February that Chief Surveillance Commissioner Sir Christopher Rose would try to report back within two weeks.
But Ms Smith told the Commons home affairs committee she had not yet received the report.
She said Mr Straw had merely "hoped" the probe might finish in a fortnight.
Sir Christopher had to be given enough time "to carry this out in a thorough way", she said.
The inquiry was prompted by claims that counter-terrorism officers secretly recorded discussions between Tooting MP Sadiq Khan and terror suspect Babar Ahmad, a constituent, he was visiting in jail.
Mark Kearney, a former police intelligence officer at Woodhill Prison in Milton Keynes, claimed the Met Police put him under "significant pressure" to bug the Labour MP. Mr Straw said Sir Christopher, a former Court of Appeal judge, would try to find out under whose authority any bugging was carried out.
He said Sir Christopher would try to complete his task within two weeks - which ended on 18 February - and would report back the results to the prime minister, home secretary and himself.