Khama, an ex-soldier and critic of Zimbabwean President Robert Mugabe

Botswana's Ian Khama was sworn in for another term as president on Tuesday after a landslide election victory in the world's largest diamond producer.

Khama, the son of the southern African country's founding president, took over the post last year and will serve a five-year term after the governing Botswana Democratic Party extended its parliamentary majority.

The BDP has won every election since independence from Britain in 1966.

The party won 45 of 57 constituencies, and about 54 percent of the popular vote, compared with just over 20 percent for the Botswana National Front.

Khama, 56, overcame divisions within his own party but faces a tougher task to revitalise an economy battered by a global crisis that led to a huge fall in demand for diamonds, which account for 40 percent of the economy.

The country of just 1.8 million people faces another double-digit contraction in the 2009/10 financial year.

In an inauguration speech outside parliament, Khama urged the private sector to work with the government to boost growth.

"While optimistic about our future, I remain conscious of the challenges brought on by the global financial crisis," he said, after deciding against a lavish ceremony to save costs.

"In this connection, the private sector must redouble its efforts in a spirit of partnership with government to grow the economy."

Botswana's economy is expected to rebound as demand for diamonds recovers in 2010, with investors looking for a return to the prudent financial management that made it one of Africa's gems.

Khama, an ex-soldier and critic of Zimbabwean President Robert Mugabe, appealed to communities to help fight poverty and vowed to stick to principles of democracy and freedom.

Botswana has long been considered one of the least corrupt countries in Africa and, before the crisis, had the highest sovereign ratings on the continent.

It has won wide praise for its battle against AIDS, offering drugs and other treatment to contain an epidemic estimated to have infected one in three adults.

However, debt has soared in the downturn and concern about human rights lingers.

Botswana faced international scrutiny in 2006 when its highest court ruled it had illegally forced San Bushmen off their ancestral lands, and in 2007 the government banned 17 people, mostly foreign journalists and human rights activists from the country.