The two opposition parties facing the People's Action Party (PAP) in Pasir Ris-Punggol GRC have turned their attention to each other instead of the ruling party - with a dispute brewing over who caused the rare three-cornered GRC fight.

The Peoples Voice party (PV) and Singapore Democratic Alliance (SDA) yesterday blamed each other for the first multi-cornered fight in a GRC since 1992, with accusations centring on an audio clip allegedly showing PV chief Lim Tean disparaging opposition unity.

Mr Lim said the SDA never contacted them to discuss overlapping claims despite SDA saying it had sent several messages to him.

He added that he had not spoken to SDA chief Desmond Lim for two years until the night before Nomination Day, when he said the SDA threatened to release an audio clip of him making remarks "against opposition unity".

"That is unbecoming behaviour for a political leader," said Mr Lim Tean. "I do not go around threatening fellow opposition leaders. I do not go around trying to negotiate or attempt to force them out of a contest on the eve of Nomination (Day)."

He added that he did not believe in "chopeing (reserving) places" and said PV has spent a lot of time walking the ground in Pasir Ris-Punggol since February last year.

Mr Desmond Lim, in turn, denied threatening PV. He said he had brought up the audio clip because he had received it from a contact and told Mr Lim Tean that the clip might be circulated.

"I just informed him that I had received a voice clip ," he said.

On Tuesday, which was Nomination Day, both had sought to position themselves as the better opposition party in Pasir Ris-Punggol.

Mr Lim Tean told reporters that PV was a greater threat to PAP dominance in Pasir Ris-Punggol GRC compared with the SDA.

That night, SDA responded with a statement saying it had faith that "residents can tell the difference between SDA and other parties that are only full of hot air".

"They are so full of hot air, that they thought they will just parachute into Pasir Ris-Punggol," Mr Desmond Lim added, stressing that SDA has been contesting in Pasir Ris-Punggol for the past three elections. "We have worked hard in Pasir Ris and Punggol for 13 years. Every day, we give free meals to needy residents and seniors and distribute essential items such as rice and baby products to poor families."

The two parties had been on a collision course since late last month when Mr Lim Tean posted on Facebook that his party will be contesting in five constituencies, including Pasir Ris-Punggol.

ST understands that no discussions to resolve the conflict ever took place.

With the three-cornered fight in place, the three parties were out distributing fliers and greeting residents at Punggol MRT station, among other locations, yesterday.

Mr Gilbert Goh, who is running on the PV ticket in Pasir Ris-Punggol, told reporters yesterday that he did have concerns about one of the opposition parties losing their deposits.

Each candidate forfeits $13,500 if the team does not get 12.5 per cent of the votes.

But he added that he hopes his decision to run on PV's ticket will not destroy his friendship with Mr Desmond Lim.

"Desmond is a good guy and I really cherish his friendship... But this is politics," said Mr Goh.