Delegates at Cosatu's 11th national congress in Midrand sang in favour of a second term for President Jacob Zuma on Thursday morning.

During a morning address, several delegates walked into the congress singing about Zuma and holding up two fingers. They were called to order by Congress of SA Trade Unions (Cosatu) general secretary Zwelinzima Vavi.

"Comrades, you are out of order. You just can't come in late and disturb the conference."

After the address, he then led the crowd in singing about Zuma, but many of the delegates refused to stop.

The majority held up two fingers, indicating their support for a second term for Zuma.

Those who supported Deputy President Kgalema Mothlanthe rolled their hands in the gesture commonly used in soccer to call for the substitution of a player.

Vavi unsuccessfully tried to get delegates to stop singing.

"There is nothing wrong about singing about the leader of the alliance, but there is something wrong about singing against any leader of the alliance," he said.

"The... rule is that we should not show signs. If we start showing signs we [will] divide the congress."

Some delegates defiantly put up two fingers while Vavi was speaking.

He spoke out on the signs during a discussion on the rules of the congress on Monday.

"We cannot spend our time in a battle with each other [before the ANC conference in Mangaung] going 'wah, wah, wah'," he said, rolling his hands and then holding up two fingers.

Cosatu's congress is scheduled to conclude on Thursday.