April 10 (Reuters) - Cameroon's national assembly adopted a constitutional bill on Thursday removing a two-term presidential limit to allow President Paul Biya to extend his 25-year rule in the central African country past 2011.

Following are some key facts about the central African country:

GEOGRAPHY - Cameroon covers 465,400 sq km (179,700 sq miles) and stretches from mangrove swamps on the Atlantic Coast through dense rainforests to the more arid north by Lake Chad. It borders Nigeria, Chad, Central African Republic, Congo Republic, Equatorial Guinea and Gabon. It is a bit smaller than Spain.

POPULATION - 18.2 million people.

ETHNICITY - Some 200 ethnic groups, with the Doualas, Bamilekes, Tikars and Baumauns prominent in the south, the Euondos and Fulbes in the west and the Fulanis in the north. There is also a Baka pygmy minority in the southeast.

RELIGION - Christian majority in the south and Muslim in the north. Half of the population practises traditional African religions.

LANGUAGE - French and English are the two official languages. About 200 African languages are also spoken (Beti and Bulu are the most prominent).

CAPITAL - Yaounde.

ECONOMY - Cameroon has the biggest economy in central Africa and is among the top 10 south of the Sahara. Economic growth is seen reaching up to 5.8 percent in 2008.

Cameroon produces around 90,000 barrels a day of oil -- about half its peak output in the mid-1980s.

It is the world's fourth-biggest cocoa producer. It also grows considerable amounts of coffee, cocoa and palm oil.

SOME RECENT HISTORY:

-- French Cameroon became independent in 1960. In 1961, the British Southern Cameroons voted to join the new republic while the British Northern Cameroons chose to merge with Nigeria.

-- President Paul Biya, 75, came to power in 1982 as the hand-picked successor of independence President Ahmadou Ahidjo. Opponents accuse Biya of undermining a robust economy. -- Biya took more than 75 percent of the vote in the latest presidential poll in late 2004.

(Writing by David Cutler, London Editorial Reference Unit;)

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