The DA in Gauteng says it has learnt that 103 extra staff posts were approved at Tembisa Hospital a year ago, but there were no funds to fill them.
In a statement on Sunday, the party's provincial health spokesperson Jack Bloom said he had uncovered this during an unannounced visit to the hospital last Friday.
Bloom said staff at the hospital's Ward 5 neonatal ICU unit informed them that only 19 staff members were working at the unit, while 40 were needed to operate it.
"At the Ward 4 neonatal ward, where most of the deaths occurred, there are 44 beds, but there were 61 babies when we visited and we were told that, in December, there were days when there were more than 100 babies," he said.
According to Tembisa Hospital CEO Dr Lekopane Mogaladi, the hospital has been managing to control Carbapenem-resistant Enterobacteriaceae (CRE) klebsiella, cases which averaged two a month from January to October last year, Bloom said.
He said the CEO had explained that the hospital had noticed it rise to five cases in November, and got really concerned when the number grew to 12 cases in December
"Overcrowding that increases the risk of cross-infection is a major problem. Instead of one metre distance between beds, nurses told us that beds were often side-to-side.
"There is only one doctor on call in the evening for the seven maternal and natal wards, which is extremely problematic if there are a number of emergency cases at any one time."
Ten babies died at Tembisa Hospital's neonatal unit between November and December last year, due to a Carbapenem-resistant Enterobacteriaceae (CRE) outbreak, News24 previously reported.
Bloom said the deaths could have been avoided if President Cyril Ramaphosa "had listened and acted effectively" when he visited the hospital in 2018.
He added that Ramaphosa had "failed" to provide extra staff and resources at the hospital, even after he promised on May 20.
He said the "failed promises" within the health sector would lead to more avoidable deaths in hospitals.