South Africa's rand hovered close to the previous session's 7 week high on Friday, supported by renewed optimism about the outlook for the global economy, while MTN led stocks lower a day after issuing a profit warning.

Analysts cautioned that the rand could resume the downward spiral triggered by the clumsy changing of finance ministers in December if next week's budget failed to convince investors that prudent fiscal policy remains intact.

The local unit had climbed to its strongest level since late December during Thursday trade as receding fears of a global economic downturn boosted risk appetite.

Next week's budget poses a risk for the rand as Finance Minister Pravin Gordhan must juggle a series of conflicting demands with limited revenue, against the backdrop of sluggish growth for Africa's most advanced economy.

"The rand may move closer to 15.00 still, but ahead of the budget next week ... upside may have become a bit compressed," Standard Bank said in a note.

"From a risk/return perspective, adding to long rand positions at this point does not add much value given the lingering event risk."

South African shares got off to a weak start, with the Top-40 index down 1.1 percent while the broader all-share fell 0.8 percent soon after the market opened at 0700 GMT.

The losses were led by mobile firm MTN, which tumbled more than 13 percent after warning the previous day that its full year profit had likely fallen at least 20 percent.

Government bonds also weakened, and the yield for the benchmark instrument due in 2026 added 5 basis points to 9.135 percent.