British and American aircraft were attacked by Iraqi missiles and multiple-rocket launchers more than 22 times in January.
Downing Street says the figure is higher than for all of 2000.
It is also said to reflect an intensification of Iraqi offensive activity since the new year.
That is believed to be linked to Baghdad's acquisition of a new fibre-optic aircraft detection system, which was targeted in Friday's air strikes around Baghdad.
The strikes brought international condemnation, headed by the Arab League, Russia, China and France.
The fibre-optic system is understood to allow Iraqi anti-aircraft units to spot allied planes from a greater distance than the conventional radar they used before.
Appeals from MPs for the British Parliament to be recalled from its week-long recess to discuss the strikes have been rejected.
British Defence Secretary Geoff Hoon told Tony Benn and other MPs no recall was necessary as the strikes did not amount to an escalation of violence or a change in policy.
Downing Street and the British Ministry of Defence are still insisting the attacks were necessary to defend the safety of allied air crew patrolling no-fly zones in the north and south of Iraq.
Baghdad said two civilians died in the raids.