The United States said Thursday it is appalled by new outbreaks of violence in Sudan's western Darfur region, attributed to the Sudanese government and its Arab militia allies, and to local Darfur rebels. The State Department said U.S. diplomats are talking with other countries at the United Nations about possible new sanctions against the parties.

Officials here are troubled and exasperated by the Darfur violence, which appears to have erupted again with full force, despite months of painstaking peace efforts and the deployment of African Union monitors.

At a news briefing, State Department Spokesman Richard Boucher decried what he said has been a disturbing set of events in Darfur in recent days.

He said they include new aerial bombings by the Sudanese government, an attack by its surrogate Arab militiamen, the Janjaweed, on a Darfur village that killed more than 100 people, including women and children, and village attacks by Darfur rebels, especially the Sudan Liberation Army:

"The question of the state of affairs in Darfur is certainly one of great concern to us," he said.  "We've been appalled by the violent clashes and blatant violations of the cease-fire that have been happening in Darfur. All the parties, the government of Sudan, the militias that are allied with the government, and the rebels are to blame for this increase in violence. It must stop immediately. As we've always said, people who have been involved in this violence must be held accountable."

Mr. Boucher said the callous air attacks by the Sudanese government are a clear violation of the Darfur cease-fire accord signed in Chad last year and more recent humanitarian protocols concluded in the Nigerian capital, Abjua.

He said they call into question Khartoum's sincerity in abiding by terms of the north-south Sudanese peace agreement it concluded with the Sudan Peoples' Liberation Movement less than three weeks ago. Similarly, he said the Darfur rebels are breaking every promise they have made with recent brazen attacks.

Mr. Boucher also said the United States joins the U.N. special envoy for Sudan Jan Pronk in expressing concern about three local staff members of  the Adventist Development and Relief Agency presumed to have been abducted by Darfur rebels in mid-December and unaccounted for since then.

He further criticized as ill advised, the arrest this week of a Sudanese human rights advocate involved with the Darfur issue, Madawi Ibrahim Adam of the Sudan Social Development Organization.

He said the arrest indicates a less than total commitment by Khartoum authorities to humanitarian pledges they have made, and urged that Mr. Adam be released or given immediate access to legal representation and medical care.

The upsurge in Darfur violence comes as a U.N. Commission tasked by a Security Council resolution last year is preparing to report to the council on accountability for atrocities in Darfur since 2003 that the United States has termed genocide.

Mr. Boucher noted that U.N. resolutions on Darfur provide for punitive measures against the various parties to pressure them to abide by peace commitments.

He said while U.S. relations with Sudan are already limited by sanctions, the Bush administration - though it prefers an international approach, is examining further penalties under the Sudan Peace Act approved by Congress last year.