By Chris Mfula

LUSAKA (Reuters) - Zambia's opposition leader accused the government on Thursday of using repressive laws to restrict his side's campaigns and said the closure of a critical newspaper would prevent free and fair elections in August.

Zambia will hold presidential and parliamentary elections on Aug. 11 in which President Edgar Lungu is expected to face opposition leader Hakainde Hichilema in another close contest after last year's neck-and-neck race.

Lungu has been in power in the southern African nation since winning election in January 2015 after the death of his predecessor, Michael Sata, in October 2014.

"The current environment, where basic freedoms are contravened by the government, does not support the desire of Zambians to have free and fair elections," Hichilema, one of Zambia's wealthiest businessmen and known locally as "HH", told Reuters in an interview at his mansion in Lusaka.

Hichilema, who heads the United Party for National Development (UPND), pointed to the closure of The Post newspaper by tax authorities as a move to muzzle the media.

He said that supporters of the ruling Patriotic Front tried to disrupt his rally on June 13 in northern Zambia and he was also barred by police from holding another meeting in the Copperbelt town of Kitwe in May.

"The closure of (the) Post newspaper is meant to deny the opposition a voice. It also means government wrongs will not be exposed, so you can't have free and fair elections," he said.

Presidential spokesman Amos Chanda denied the accusations, saying that the opposition was campaigning freely.

"Everybody has obligations to pay tax. The supreme court ruled in favor of the ZRA (Zambia Revenue Authority). It is purely between The Post and ZRA," Chanda said.

Hichilema said his party would diversify the economy by improving agriculture, tourism and energy, and abolish value added tax on room rates to draw in tourists to help boost foreign exchange earnings.

Zambia is Africa's second biggest copper producer.

He blamed Lungu for a weakening currency that has lost about 20 percent since April.

"We expect to increase tourist inflows and when we increase tourist inflows we improve the supply side of the dollar. When we do that the kwacha will appreciate and stabilize," he said.

Hichilema said he backed austerity measures by the International Monetary Fund to curb government spending.

"The IMF programs are talking about reducing expenditure and we are talking about reducing expenditure. There is common ground in what we plan to do," he said. The IMF is due to hold talks with Zambian officials after the elections.

Zambian inflation stood at 21.3 percent in May and Lungu has said he expected the rate to slow to single digits "within months", while the economy is expected to grow to 3.7 percent this year from 3.5 percent last year.

The presidency's spokesman, Chanda, said Lungu took power when the country faced a huge budget deficit and fuel shortages.

"Of course the kwacha is not where the president would want it to be, but it is slowly improving," Chanda said.

(Writing by James Macharia; Editing by Mark Heinrich)