President Kgalema Motlanthe on Friday denied the independence of South Africa's judiciary was being undermined.

"Recent assertions in the local and international media that the judiciary is being undermined are untrue, and without basis," he told the World Conference on Constitutional Justice in Cape Town.

"There is a serious and necessary debate and a contestation regarding the balance of power between the judiciary, the executive and the legislature," said Motlanthe, who last month fired national prosecutions chief Vusi Pikoli.

He said tension between the three arms of government was par for the course in a democracy.

"It is common cause that constitutional democracies across the globe are characterised by the inherent and indeed necessary tensions between the three arms of government which must necessarily co-operate even as they discharge their mandates," he said.

"There is no common approach through which different countries have organised and managed the at times contentious relationship between the three arms of government."

Pikoli was sacked for being insensitive to national security issues,

He maintains the real reason for his removal was his refusal to bow to pressure from former president Thabo Mbeki and his justice minister, Brigitte Mabandla, not to arrest now suspended national police commissioner Jackie Selebi.

Pikoli has been fighting for his career before an ad hoc parliamentary committee which must advise MPs by month's end on whether or not to endorse Motlanthe's decision.

The committee heard this week from the director general in the presidency, Frank Chicane, that Mbeki was "shocked" when Pikoli produced an arrest warrant for Selebi in September 2007 while the presidency was still expecting a report into the case.

"The moment was tense. Mr Pikoli had decided to go his own way," he told MPs.

According to Chicane, Mbeki suspended the prosecutor not to prevent Selebi's arrest but because he knew the arrest could destabilise the country and wanted to put in place safeguards before letting Pikoli proceed.