Discussions initially focussed on Fiat Chrysler (FCA) using platforms and technologies from Renault have reportedly morphed into something more complex and wide-ranging.
The sources have cautioned the discussions could still fall apart and yield no deal.
Renault's relationship with its Japanese partner has been strained since the arrest of former CEO Carlos Ghosn, with the French car maker still keen on merging the two companies, but Nissan resistant to anything which would allow the French to entrench control.
It's unclear how involved Nissan has been in the talks so far, with some sources uncertain, and one stating explicitly Nissan hasn't been included at this stage.
In late March, Nissan's CEO said he was unaware about Renault's reported desire to merge with or take over Fiat Chrysler.
Talks between FCA and PSA reportedly broke down due to concerns about the merged automaker's over-reliance on Europe and how PSA would fund the acquisition.
Both automakers have previously gone on the record stating they were willing to have discussions with any interested party about collaboration or consolidation.