As part of a wider privatisation drive and to streamline Sonangol, the government said last week the process to sell the Puma stake would start in a few days. Sonangol has been a shareholder since 2011, when it bought an initial 20% stake.
The move comes after Puma abandoned a new bond issue announced in late September.
The firm has been loss-making for nearly three years and faces further problems due to the COVID-19 pandemic, which has devastated fuel demand.
Puma was downgraded by ratings agencies in 2019 despite efforts by a new management team to sell assets to shore up its balance sheet, including the divestment of its Australian business to Chevron, completed in June.
It was also looking to sell some peripheral assets in west Africa later this year, the source said. The company said it was "on track" to divest a further $100 million of assets this year.
Jefferies declined to comment. Sonangol did not respond to requests for comment.
"The bond was meant to refinance an around $600 million bank loan maturing next May. The market is choppy, especially for companies with a weaker rating," the source said, adding that Puma was unlikely to try to raise money again before the year-end.
Pulling the bond may mean Puma will have to ask the banks for an extension on its loan, the source said.
A Puma spokesman said the loan has an extension option. He added that it has paid back $200 million this year, and expects to make a further payment in the fourth quarter.
Puma has an untapped credit line from Trafigura valid until 2023.
"There were a number of factors at play, and Puma's board decided not to proceed with the bond issuance," the spokesman said.
Trafigura had hoped to list Puma, but the share register, which also included a retired Angolan general, stymied the process due to compliance hurdles.
(Reporting by Julia Payne; Editing by Pratima Desai and Jan Harvey)
By Julia Payne