But Blair told a House of Commons committee today that he believes the prospects for democracy in the country remain good.
Blair's comments came one week after Afghan Defense Minister Abdul Rahim Wardak said Al-Qaeda had smuggled cash, weapons, and explosives into the country to prepare for an insurgency campaign against the government.
Also today, Blair said his government had been overly optimistic in its goals to eradicate opium production in Afghanistan.
Britain has led a counternarcotics coalition in the country since 2001.
However a U.S. report said earlier this year the area in Afghanistan devoted to poppy cultivation last year set a record of more than 200,000 hectares, more than three times the figure for 2003.