President Kgalema Motlanthe has a week to reverse a decision not to appoint an arms deal commission of inquiry or face a lawsuit for allegedly violating the constitution.

Motlanthe last month rejected calls by leading South Africans, including Nobel laureates Desmond Tutu and FW de Klerk, as well as the late Helen Suzman, to appoint a commission of inquiry in the arms deal.

A 10-page letter of demand was served on the president at his Tuynhuys office in Cape Town this week and he has until Friday to change his mind.

If he refuses, he is accused of an "awkward conflict of interest" and having placed the ANC's interests above the nation's.

While Tutu is on record as saying he was "deeply disappointed" by Motlanthe's inaction, neither he nor De Klerk are potential litigants.

Anti-arms deal campaigner and author Terry Crawford-Browne, who, along with Cape Town advocate Paul Hoffman, spearheaded the renewed campaign for an arms deal inquiry, have taken up the legal cudgels instead. "He [Tutu] is not involved and neither is Mr De Klerk. They would not be appropriate litigants," Crawford-Browne said.

The retired banker has failed in previous arms deal-related court battles against Finance Minister Trevor Manuel.

The latest legal action would be unprecedented if it gets to the courts, with experts divided over whether a head of state could be forced to appoint a judicial commission of inquiry, given the president's constitutional prerogative to decide.

However, Crawford-Browne argues that Motlanthe did not conduct himself in a manner "that the law requires, reasonably and accountably, or even rationally".

"The … president has placed himself in a most awkward constitutional position wherein he is seen as a placing the interests of the ANC before those of the country.

"It is the president's constitutional responsibility to appoint commissions of inquiry. This responsibility has to be discharged legally and rationally with due regard to the foundational values of our constitutional democracy."

These included the principles of accountability, openness, transparency and responsiveness to the people's needs.

This required that the president should deal properly and proactively with the allegations of corruption and impropriety, Crawford-Browne said.

The letter of demand refers among other things to former ANC MP Andrew Feinstein's allegation - made under oath - that the ANC was funded by the proceeds of arms deal corruption.

It also refers to ANC president Jacob Zuma - who is likely to succeed Motlanthe. It states that "perhaps most menacingly of all", Zuma had "let it be known that if he is convicted on the corruption charges he possibly faces, others will be exposed by him".

It repeats allegations that British Aerospace paid bribes of about R1.7-billion to secure its contracts with South Africa and that a British government minister admitted during 2003 that such "commissions" were paid, but "within reasonable limits".

The letter rejects many of Motlanthe's reasons for not establishing a commission - contained in his brief written reply to Tutu and De Klerk last month.

The letter states that laying criminal complaints was an inadequate panacea. The Scorpions unit, for example, was being disbanded, with no adequate substitute in place, while there was no chief of police or national director of public prosecutions, it states. Deputy Justice Minister Johnny de Lange has acknowledged in parliament that the criminal justice system was dysfunctional.

This all pointed to a commission of inquiry being the only viable and sustainable option available for draining "the poisoned well" of the country's body politic, the letter states.

Moreover, those who in the past had placed information of criminal wrongdoing before the authorities had received no response beyond an acknowledgment of receipt of their requests and charges.  *1

Significantly, the president had also failed to deal with the civil-law ramifications. This was a "startling omission" indicative of "a cavalier and ill-considered approach, or worse, a complete failure to apply your mind to what is a perfectly reasonable request", the letter adds.

Presidential spokesperson Thabo Masebe was not immediately available for comment.

With acknowledgements to Angela Quintal and The Star.

•  to assist the German prosecuting authority in its request for Mutual Legal Assistance (MLA) from the French government.