187 27.08.2013 National Assembly speaker Max Sisulu, at constitutional court after the court dismissed application of no confidence in president Jacob Zuma, which it was brought to court by SA. Picture: Itumeleng English

Johannesburg - The ANC on Thursday dismissed rumours that former National Assembly speaker Max Sisulu resigned after he was summoned to a meeting in connection with the investigation into President Jacob Zuma's Nkandla homestead.

“We want to dispel an unfounded rumour that comrade Max resigned after he had been summoned to a meeting at the ANC headquarters pertaining to the Nkandla investigation,” ANC spokesman Zizi Kodwa said.

“This mischievous assertion seeks to second guess reasons behind comrade Max's decision. We appeal for all those who are spreading these lies to desist from such and respect his decision.”

In April, Sisulu said he wanted to establish an ad hoc committee to investigate the security upgrades at Nkandla, KwaZulu-Natal.

Public Protector Thuli Madonsela found that Zuma and his family unduly benefited from R246 million in security upgrades to his private Nkandla homestead.

These included a swimming pool, a cattle kraal, and an amphitheatre. She recommended, among other things, that he repay a portion of the money.

In mid-May, government said a security cluster of ministers would approach a high court for a judicial review of Madonsela's report.

Kodwa said Sisulu resigned by submitting a notice to the Chief Whip of the African National Congress, Stone Sizani.

He said no “substantive reasons” were given for the resignation.

“The ANC wants to put it on record that ANC members can exercise a choice to serve in Parliament or they can withdraw that decision if they chose so,” he said.

Spokesman in the office of the ANC Chief Whip in Parliament, Moloto Mothapo, thanked Sisulu for his hard work and the dedication with which he had served South Africa. “We are grateful for the continued commitment that he continues to show as the stalwart of the ANC in serving the people of South Africa,” he said.

“Even though it is unsolicited, we are humbled and grateful for the excellence by which he has served as the speaker of fourth national Parliament.”

Sisulu is the second ANC MP to resign since Zuma announced his new Cabinet on Sunday.

Zuma replaced Sisulu with Baleka Mbete.

Former tourism minister Marthinus van Schalkwyk resigned from Parliament on Monday.

Zuma on Sunday shifted Science and Technology Minister Derek Hanekom into the tourism portfolio, leaving Van Schalkwyk - who has served as a Cabinet minister for the past decade - out in the cold and set to serve as an ordinary ANC MP.

Sisulu's and Van Schalkwyk's future plans remain unknown.