The two were travelling in an armoured Land Rover five miles east of Shaibah, in the British-patrolled Basra province, when the device detonated at 11.30am local time (8.30am UK time).
No details of the soldiers' identities or regiments are being released until next of kin have been informed, the MoD in London said.
Britain has 8,500 soldiers in Iraq. Today's casualties bring the British military death toll to 94 since the outbreak of hostilities in Iraq in March 2003.
An MoD spokesman said: "We can confirm that two soldiers from Multi-National Division South-East died this morning at 11.30 local time from injuries sustained in a roadside bomb explosion in Basra province.
"They were travelling eight kilometres (five miles) east of Shaibah in an armoured Land Rover. Further details will be posted on our website when next of kin have been informed."
The airbase at Shaibah, about 10 miles south-west of Basra, is the British logistics headquarters for Operation Telic.Reuse content