(Adds prime minister quote, security row, paragraphs 8-11)

ACCRA, July 1 (Reuters) - A rocket attack against Ivory Coast's prime minister shows the need to speed up the peace and disarmament process in the West African country, the African Union's top diplomat said on Sunday.

Opening a three-day summit of African heads of state in Accra, Ghana, AU Commission Chairman Alpha Oumar Konare condemned Friday's attack against the plane of Prime Minister Guillaume Soro, in which four aides were killed.

The incident shocked Ivory Coast as the government and rebels, who fought a brief 2002-2003 civil war that divided the world's top cocoa producer, were moving to implement a March peace deal that aims to reunite the country.

The peace pact signed in Burkina Faso's capital Ouagadougou between Ivorian President Laurent Gbagbo and New Forces rebels foresees disarmament and reunification leading to national elections early next year.

"The odious attack against the Ivory Coast prime minister calls for acceleration of the Ouagadougou (peace) process and particularly the disarming of the various groups," Konare told the summit.

"We need to support the Ouagadougou agreement, the initiative of our Ivorian brothers," he added.

Several people have been arrested after Friday's attack in the rebel stronghold of Bouake, which analysts have suggested may have been carried out by disaffected New Forces fighters angry over the peace deal that led to their former leader Soro being appointed prime minister.

In his first public comments since the attack, Soro echoed Gbagbo's comments on Saturday that some were intent on thwarting progress on the new peace plan.

"We have the duty to continue. We were more or less expecting things like that," he told a delegation of opposition party members who had come to Bouake to express their sympathy.

"I had even said the conquest of peace is a bit like a war. We were determined to lead the war of peace. It has started," he said.

New Forces officials have criticised the country's United Nations mission of more than 7,000 peacekeepers for failing to secure Bouake's airport, but the mission says it has stationed troops there only for the protection of its own aircraft.

Gbagbo has said the attack will not derail the peace agreement, but some Ivorians fear it will damage the spirit of reconciliation and goodwill that had swept the country after the signing of the March pact.

(Additional reporting by Salim Bamba in Bouake)

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