The sources said the bank was seen conducting sell-buy swaps in the dollar-yuan pair, alongside its purchases of dollars from exporters and other corporate clients.
"The big bank has been buying quite huge amounts of one-year dollars in the swap market," said one source, speaking on condition of anonymity.
The rand had earlier in the session struggled to make meaningful gains as scheduled power outages by state utility Eskom dragged into their sixth day and weighed on sentiment.
Eskom said on Monday that it aimed to get its power plant performance to "acceptable levels" by late 2021.
The rand was 0.44% stronger at 14.5550 per dollar, little moved from its overnight close of 14.6200.
There has been a divergence of views among traders this year over just how US President Joe Biden's planned $1.9 trillion fiscal stimulus package will affect the dollar.
*The pound fell in early trade after risk sentiment ebbed overnight in US and Asian markets.
* sterling was up 0.3% against the dollar at $1.3720 and was also up 0.3% against the euro, at 88.60 pence.
Rand was 0.46% weaker at 15.2400 per dollar, marking a third consecutive session of losses as investors took a more circumspect view of the pace of the global economic rebound.
The United States $1.9 trillion fiscal stimulus plans and the likelihood of developed market central banks keeping liquidity taps open.