Cape Town - A court bid to compel the four biggest political parties to reveal the source of large private donations received between January 1 2003 and May 1 2004, gets underway on Thursday.

The Institute for Democracy in South Africa (Idasa) launched its action in the Cape Town High Court in November 2003.

The African National Congress, the Democratic Alliance, the Inkatha Freedom Party, the New National Party, and the African Christian Democratic Party opposed the application, and the matter was postponed.

All four filed answering affidavits at the time.

The ACDP has decided since then to reveal the extent of private funding it received, and the application against the party was withdrawn.

According to Idasa director Paul Graham, for years the parties have been ignoring legitimate requests for information on the source of private donations they received.

He said political parties were public bodies, and the information was being sought under the Promotion of Access to Information Act.

In its heads of argument to be presented to Judge Ben Griessel on Thursday, Idasa said the application was to establish the principle that political parties were obliged to give details of their substantial private donations to those asking for the information.

This should be subject only to the provisions of chapter 4 of the Promotion of Access to Information Act.

Idasa said disclosure of donations was required for the proper functioning of a multiparty democratic system of government, and to ensure accountability, responsiveness and openness.

Disclosure helped to ensure parties and candidates did not stray from their task of serving the voter.

Citizens needed to know to whom a party, its office bearers and members might be beholden, on the basis that "he who pays the piper calls the tune".

Disclosure of the identity of major donors was necessary to ensure parties and candidates were free of inappropriate obligations.

Idasa was seeking access only to records of donations above R50 000.

The purpose of this was to compel disclosure only in respect of donations that were sufficiently substantial to influence a political party, its office bearers and its members.

The case has been set down for two days.

With acknowledgements to Iaine Harper, Sapa and News24.