Inkatha Freedom Party leader Mangosuthu Buthelezi said on Friday that he was horrified by calls that President Thabo Mbeki break his vow of office in relation to charges faced by former deputy president Jacob Zuma.

"I am horrified by Cosatu's call to the President to break his oath of office, as well as breach the Constitution, by interfering in the administration of justice in respect of the Zuma case," Buthelezi said in a statement.

"I am even more horrified that there has not been widespread condemnation of such conduct.

"When the ruling body of our largest trade union calls for the breaching of our constitutional order, one would imagine that the whole of civil society would rally in defence of our legal system and in support of the president.

"At this tragic moment for our democracy, I wish to express my support to President Mbeki for standing by the rule of law and defending our Constitution, and call on him not to interfere in the administration of justice."

Earlier this week the central committee of the Congress of SA Trade Unions called on Mbeki to reinstate Zuma as deputy president of the country and to ensure his corruption charges are dropped.

Zuma was sacked earlier this year and goes on trial in October on two charges of corruption emanating from the fraud and corruption conviction of his former financial adviser Schabir Shaik.

Zuma's home and offices of his associates, including his legal advisers, were raided on Thursday as part of the investigation towards the trial.

With acknowledgements to Sapa and Independent Online.