(adds detail from army spokesman)

KHARTOUM, April 9 (Reuters) - Seventeen Sudanese soldiers were killed in clashes with Chadian troops inside Sudanese territory, a Sudanese army spokesman said on Monday.

The spokesman, who asked not to be named, told Reuters Chadian troops backed by about eight tanks and 100 off-road vehicles crossed the border and attacked the Sudanese troops about 2 km (1 mile) inside Sudan's border.

He said the Chadian troops opened fire first, killing 17 Sudanese soldiers and a number of civilians.

A source at the Chadian presidency denied any fighting had taken place between Chadian troops and the Sudanese army.

Mohammed Aghbash, the armed forces chief official spokesman, earlier told Sudanese state television 17 Sudanese troops had been killed in border clashes with Chadian troops.

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