Egypt fired missiles at suspected militants on the Sinai peninsula on Wednesday, following an attack on security checkpoints at the weekend, al Jazeera television reported on Wednesday, citing military officials.
Some 20 people were killed in the strikes which followed clashes between gunmen and Egyptian security forces near the town of al-Arish, officials said.
The violence comes after 16 Egyptian border guards were killed in an attack on Sunday which Egyptian officials blamed on Islamic militants.
Egyptian President Mohamed Morsi pledged earlier this week to retaliate and several gunmen have been killed since Sunday's attack.
Egypt has shut down its border crossing with the Gaza Strip, as it hunts the remaining gunmen.
There has been an increase in violence on the peninsula since a popular uprising toppled former Egyptian President Hosni Mubarak last year.
One of the checkpoints involved in Wednesday's clashes has been attacked 28 times since the 2011 uprising, the state-run MENA news agency said.
Hundreds of people took to the streets of al-Arish after the clashes calling for state protection.