Campaigners have called for justice not vengeance following the terrorist attacks in the US.
Members of Lewes CND said they feared any US plans to indiscriminately bomb civilians in the Middle East may lead to World War III.
At a rally by a Lewes war memorial they urged Prime Minister Tony Blair to tell President George W Bush to find the perpetrators of the attacks and bring them to justice.
Norman Baker, Liberal Democrat MP for Lewes, attended the event. Passers-by beeped their car horns in support and signed a petition.
Lewes CND co-ordinator Anna Rehin, 72, said: "If Bush authorises the killing of civilians we may have another war on our hands. It would be totally counter-productive for the US to bomb Afghanistan or anywhere else. It would create a breeding ground for terrorists."
MP Norman Baker said: "I strongly support efforts to identify those responsible and bring them to trial for murder.
"At the moment, the sympathy of almost the entire world is with the American people but if they were to kill civilians, it would take away their moral high ground."
The Lewes CND group will be urging people to sign their petition at the war memorial in School Hill, Lewes every day this week.
A peaceful vigil was held yesterday outside the services recruitment centre in Queen's Road, Brighton, near the Clock Tower.
Demonstrators called for justice rather than vengeance and a non-violent response to the events of September 11 in the US.
Meanwhile at the Green Party's annual conference in Salisbury, Brighton and Hove councillor Rik Child said he was horrified that America was apparently refusing to rule out a nuclear attack in retaliation.
He said: "We utterly reject such a policy, believing it to be profoundly morally wrong in itself. We also fear that it would be highly dangerous in terms of its potentially escalatory consequences.
"We believe that violent counter-measures of any type would be a sure way of creating more suicide bombers, willing to martyr themselves in protest.
"We support the United States Green Party in its statement that while justice is clearly imperative, there is no security in revenge.
"We also call on the people of the world's most powerful countries to reflect on why the attacks took place at all.
"We should have the humility to recognise that dominant attitudes and lifestyles in our countries may have some part to play in leading to such attacks, and may continue to do so."
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