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BAGHDAD, April 25 (Reuters) - Nine people were killed and 16 others were wounded in an attack by a suicide bomber inside a police station northeast of Baghdad on Wednesday, police said.

The bomber walked into the police station in Balad Ruz, 50 km southeast of Baquba, the capital of volatile Diyala province.

Diyala is a region with a mixed population of Sunni Arabs and Shi'ites where U.S. forces are engaged in fierce fighting with entrenched insurgents and al Qaeda militants.

Nine U.S. soldiers were killed and 20 wounded in an attack by two suicide truck bombers on a military outpost near Baquba on Monday, one of the worst attacks on U.S. forces since the U.S.-led invasion in March 2003.

On Tuesday, gunmen wearing Iraqi army uniforms killed six people and wounded 15 in a Baquba neighbourhood.

Tens of thousands of U.S. and Iraqi forces have been deployed in Baghdad since February as part of a security crackdown aimed at stopping Iraq from sliding into all-out sectarian civil war.

That crackdown in the capital has prompted insurgents to focus their attacks more on provinces outside the capital.

(Writing by Paul Tait, editing by Dean Yates)

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