An independent audit of the 2019 general election results is the only remedy to legitimise them.

This is the assertion of DA leader Mmusi Maimane, who on Thursday joined smaller opposition parties in complaining about alleged irregularities in the May 8 polls - including allegations of double-voting by some voters.

Maimane said the DA believed an independent audit of all the election results was the only way of resolving the dispute, indicating that should the audit reveal irregularities then his party could take further steps.

Maimane made the comments as his party struggled to increase its national support to its expected level, amassing only electoral support of 22.58% just before 7pm on Thursday night, which represented a marginal increase from the 22.23% it gained in 2014.

At that time, just under 60% of the national ballots had been counted.

The DA leader was addressing the media on Thursday night on his first visit to the IEC results operation centre in Tshwane.

"We have got concerns over the electoral process in how some of the issues have been handled. I am concerned that many South Africans were able to vote twice," said Maimane.

"And therefore I call for an audit, it is very important. This needs to be interrogated.

"Of course I want free and fair elections, it is good for democracy. We must make sure that elections are the reflection of the will of the people, if they are not then it cannot be legitimised. We are waiting now to make sure that audit defines what the material outcomes of it is and then we will take the conversation from there."

Maimane's remarks followed other complaints over the credibility of the elections from smaller opposition parties.

The parties, led by ATM's Mzwanele Manyi, told reporters that they were "not convinced that these elections are free and fair".

This group, unlike Maimane, does not believe auditing is the way.

Instead, they called for a re-run of the elections.  

The disgruntled group, made up of new parties, included the BLF, Socialist Revolutionary Workers Party and Forum for Service Delivery, among others.