By Tanisha Heiberg

PRETORIA (Reuters) - South African President Jacob Zuma failed on Friday in his appeal against a court ruling that corruption charges against him be reinstated, another setback for the leader who has been facing calls for his resignation.

The ruling puts further pressure on Zuma after a damning constitutional court judgment against him in March, and comes six weeks before local elections at which the ruling African National Congress faces a strong challenge from opponents seeking to capitalize on what they see as his missteps.

The rand cheered the ruling by the High Court in Pretoria, paring some losses after it fell more than 8 percent to the dollar in the wake of Britain's shock referendum vote to leave the European Union.

The court said Zuma and National Director of Public Prosecutions Shaun Abrahams, who had appealed the earlier ruling alongside the president, had no grounds to do so.

"The matter is of course important for Mr Zuma. However if the appeal does not have reasonable prospects for success, leave to appeal should not be granted," Judge Aubrey Ledwaba said.

It was not immediately clear if Zuma would appeal Friday's ruling, but legal analysts said both he and the National Prosecuting Authority (NPA) could still lodge a petition to the Supreme Court of Appeal.

Ledwaba had in April ordered a review of a 2009 decision by the NPA to set aside hundreds of charges against Zuma, which he described in his ruling as "irrational". That decision by the NPA allowed Zuma to run for president the same month.

Then-national prosecutor Mokotedi Mpshe's decision was based on phone intercepts presented by Zuma's legal team that suggested the timing of the charges in late 2007 may have been part of a political plot against him.

The hundreds of corruption charges against Zuma relate to a major government arms deal in the late 1990s.

Zuma said in April that a government investigation into the arms deal had found no evidence of corruption or fraud but critics denounced the findings as a cover-up.

ANC spokeswoman Khusela Sangoni declined to comment on the ruling, referring questions to the Presidency where no official could be reached for comment.

The opposition Democratic Alliance party said Abrahams should now file the graft charges against Zuma, adding that "no man is or should be above the law".

ZUMA SCANDALS

The South African leader has been beset by scandal during his tenure, but has managed to hold on to his post with backing from the ANC, which has been in power since the end of white-minority rule in 1994.

In April, he survived an impeachment vote after the Constitutional Court said he broke the law by refusing to refund some of the 240 million rand ($16 million) of state money spent on refurbishing his private residence.

In December he was widely criticized for changing his finance minister twice in a week, sending the rand plummeting.

Record unemployment and a looming recession have exacerbated discontent with Zuma's leadership. Analysts said his credibility was on the line once more.

"There is no question that a poor result in the August election, alongside an impending corruption case against Jacob Zuma, might fragment the currently very solid voting support he has within the ANC structures," BNP Paribas Securities South Africa political analyst Nic Borain said.

(Additional reporting by Zimasa Mpemnyama in Johannesburg; Writing by James Macharia; Editing by Ed Cropley)