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By Betel Miarom

N'DJAMENA, March 22 (Reuters) - Chad said on Thursday warplanes from neighbouring Sudan had bombed two towns in its violence-plagued east, killing several people and violating a non-aggression pact signed last month.

Chadian President Idriss Deby's government said two bombers had been pounding the settlements of Kariari and Gregui near the lawless eastern border with Sudan's Darfur region since Wednesday, causing heavy material damage.

The central African states agreed in February in Libya to end border violence fuelled by the conflict in Darfur, where an estimated 2.5 million people have been uprooted and some 200,000 killed in a political and ethnic conflict raging since 2003.

Chad's Secretary of State for Foreign Affairs, Djidda Moussa Outman, summoned Sudan's ambassador to deliver a strong protest and call on Khartoum to stop the attacks.

"The Chadian government reserves the right to use all available means to assure the defence of its territory," read a communique signed by government spokesman Hourmadji Moussa Doumgor.

Chad and Sudan have long accused each other of supporting rebels groups fighting against their respective governments.

It was the second time in five months that Chad has said Sudan had bombed its territory. In October, N'Djamena said four Sudanese planes bombed four border towns. Khartoum dismissed the statement as propaganda.

At a summit last month convened by Libyan leader Muammar Gaddafi, Chad and Sudan agreed not to interfere in each other's internal affairs and "refrain from any hostile activity against one another".

It was their third such agreement in 12 months.

Some analysts fear violence spilling over from Darfur could destabilise the wider region, fuelling rebel activity both in Chad and in neighbouring Central African Republic.

The U.N.'s new humanitarian and emergency relief coordinator John Holmes is currently in Sudan and is due to travel on to the country's two western neighbours over the next 10 days.

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