Small blast near top Nigerian politician's house

ABUJA, Mar 27 (Reuters) An explosion injured one worker near the home of one of Nigeria's most prominent politicians, police said today.

The man picked up a device, thought to be a grenade, outside the house of Deputy Senate President Ibrahim Mantu who is at the forefront of a divisive campaign to change the constitution so President Olusegun Obasanjo can stay in power for longer.

The man suffered injuries to his arms, stomach and legs.

Explosives experts combed the area around the house.

The incident comes at a time of heightened political tensions in Africa's most populous country ahead of elections next year. Violence, some of it linked to political power struggles, has been on the rise.

Nigeria returned to civilian government in 1999 after three decades during which it was ruled by the army most of the time.

Ethnic and religious violence has killed at least 14,000 people since 1999. Political violence increased dramatically before the last election, in 2003, and many fear the build-up to 2007 could also turn ugly.

Mantu is a controversial figure because he heads a parliamentary committee on constitutional change that many Nigerians believe is geared exclusively towards achieving a third term as president for Obasanjo.

The constitution as it stands prevents Obasanjo, who has been president since 1999, from standing again in 2007. But many powerful allies are pushing for a change to the charter that would allow him to seek a third term.

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