JOHANNESBURG (Reuters) - South African President Jacob Zuma and Finance Minister Pravin Gordhan sat side-by-side on Friday in a show of solidarity after weeks of speculation that the pair are locked in a bitter power struggle.


The pair appeared together at a news conference where they both stressed the need to work together to address South Africa's economic problems.


There was no mention of an ongoing police investigation into Gordhan. Local media have reported that the minister could be arrested for his part in a surveillance unit at the tax agency he once led, while Zuma's opponents have described the investigation as a politically driven witch-hunt.


Potentially easing the pressure on the minister, a book published on Friday by Johann van Loggerenberg, an apartheid-era policeman who ran the so-called "rogue unit" at the South African Revenue Service (SARS) before resigning in early 2015, said Gordhan played no part in its operations.


"Gordhan never had anything to do with the unit in any manner or form. He didn't meet officials, he didn’t directly task the unit and he certainly never received any reports from them," van Loggerenberg said in the book, entitled 'Rogue, the inside story of SARS's elite crime-busting unit'.


Van Loggerenberg quit after a series of stories in South Africa's Sunday Times newspaper alleged that the unit was behind illegal spy operations targeting Zuma, while also running a brothel.

In April, nearly two years after its "rogue unit" expose, the Sunday Times published a full-page article retracting its claims against van Loggerenberg and other senior officials.

The investigative unit, which operated in SARS between 2007 and 2014, was created to bring high-level fraudsters and tax criminals to justice, although its work was blunted by mass resignations and political infighting, the book said.

The perceived rifts between Zuma and Gordhan have rattled markets in Africa's most industrialized economy, which faces the risk of ratings downgrades later this year.

At the news conference, Zuma urged politicians, business leaders, the public and the media to be more positive about South Africa, following shows of dissent by members of the ruling African National Congress in recent weeks.

Divisions within the ANC have widened since it suffered its worst-ever local election results last month.

"The meeting appeals to all in our country to refrain from making public utterances that promote a negative narrative about the country," the president said.

(Reporting by Joe Brock and Wendell Roelf; Editing by Mark Trevelyan)