* Khama secures re-election

* BDP gets majority in expected election win

* Recession, infighting represent challenges for BDP

By Serena Chaudhry

GABORONE, Oct 18 (Reuters) - Botswana's President Ian Khama secured a new five-year term, extending his rule over the world's largest diamond producer, after his governing BDP party swept to victory on Saturday in a parliamentary election.

Chief Justice Julian Nganunu said Khama, son of the country's first president, would remain at the helm of the southern African nation, which is battling a recession and hit by internal party squabbling.

"I have the honour and privilege to declare Ian Khama Botswana's president as his party has garnered more than enough seats," Chief Justice Julian Nganunu said on state radio.

The winning party needs to win 29 of the 57 parliamentary seats to select the president. The Botswana Democratic Party (BDP) -- in power since independence in 1966 -- had won 36 of the 57 constituencies with counting in 45 completed, according to official results.