JOHANNESBURG (Reuters) - South Africa's deputy finance minister said on Thursday that patronage and corruption were undermining efforts for a credible government, a day after an audit showed the government had made $3 billion in irregular expenditure this financial year.

South Africa's political elite has been involved in a slew of corruption scandals which have eroded the trust of investors and weighed on Africa's most industrialized economy. Ratings agencies have warned of downgrades before the end of the year.

Mcebisi Jonas' remarks in a speech at a labor congress came a day after the auditor-general said irregular expenditure by government departments swelled 80 percent to 43.4 billion rand ($3 billion) in the 2015-16 financial year.

"Leadership that looks beyond its own narrow confines is needed," Jonas said, adding that "patronage and corruption had undermined efforts to build a credible government".

Last week President Jabob Zuma survived a parliamentary no-confidence vote over allegations of influence-peddling, one of several scandals involving him since taking office in 2009. The 74-year-old has shown no intention of wanting to resign.

As deputy finance minister, Jonas has been an outspoken critic of government graft. In October he said "Corruption is real, it's palpable, you can feel it."

On Thursday he also said that ratings agencies were concerned about Pretoria's ability to maintain fiscal targets but Treasury had "convinced them" that it could maintain caps on spending.

"We've done what could be done. My sense is that there is general acceptance of the constraints," Jonas told reporters after his speech.

(Reporting by Mfuneko Toyana; Writing by Ed Stoddard; Editing by James Macharia and Raissa Kasolowsky)