BAGHDAD  A suicide bomber killed 30 people at a funeral in Diyala Province on Thursday, and a fierce dust storm that blanketed much of Iraq provided cover in Baghdad for intensified rocket attacks into the fortified Green Zone.

The bombing, at a funeral for two Sunni tribesmen, was the second major suicide attack in three days in the northern province, which the American military says has largely been wrested from the control of insurgents. On Tuesday a suicide car bombing in Baquba, the provincial capital, killed at least 40 people.

Fierce fighting continued Thursday in the Sadr City neighborhood of Baghdad. American and Iraqi forces are seeking to stop Shiite militias from using the area as a firing ground for rockets and mortars aimed at the Green Zone, where Iraq’s central government and the United States Embassy are housed.

According to the embassy, no one was wounded Thursday in the attacks on the zone. Rocket and mortar fire on the Green Zone have dropped off significantly in recent days after a few weeks when there were multiple attacks daily.