South African President Jacob Zuma failed to "uphold, defend and respect" the constitution when he ignored the order of an anti-corruption watchdog to repay some of the $16m spent to upgrade his private home, the Constitutional Court has ruled.

After delivering a stinging rebuke to the scandal-plagued leader on Thursday, the court gave Zuma 105 days to repay the "reasonable cost" of non-security-related upgrades to his sprawling rural residence at Nkandla in KwaZulu-Natal.

The unanimous ruling by the 11-judge court is the latest twist in a six-year saga over Nkandla that now adds financial damage to the political wounds it has already inflicted on Zuma.

South African President Jacob Zuma violated constitution

After the ruling, the top six leaders of Zuma's ruling African National Congress said they would meet to discuss the outcome of the case, a party spokeswoman said.

The decision was a vindication of Public Protector Thuli Madonsela, a constitutionally mandated watchdog who was described by chief justice Mogoeng Mogoeng as a "Biblical David" fighting against the Goliath of corruption.

On Thursday, Madonsela said early estimates indicated Zuma might have to repay the government at least $680,000. 

The uncompromising nature of the verdict - Mogoeng described it as a "profound lesson" for South Africa's young democracy - piles more pressure on Zuma, already feeling the heat from a string of scandals.

Standing outside the court in downtown Johannesburg, opposition leader Mmusi Maimane told reporters Zuma should be removed from office and said he would table a parliamentary motion to have him impeached.

Zuma, a 73-year-old Zulu traditionalist, has been under fire since December, when his abrupt sacking of finance minister Nhlanhla Nene sent the rand into a tailspin.

Judicial independence

The rand firmed to a near-four month high against the dollar as Mogoeng delivered his ruling.

The African National Congress' majority in parliament is likely to give political cover against any attempt to impeach Zuma, but the ruling may embolden opponents within the ruling party to challenge him.

In an interview with Al Jazeera, Ayesha Kajee, a political analyst, said the ruling signalled "the beginning of the end" for the president "but not quite his deathbed yet".

Economic equality still elusive in South Africa

Kajee also said the opposition did not have "sufficient numbers in parliament to impeach" Zuma, who she said still enjoyed support from rural voters. 

But for many South Africans, Kajee said the court's decision was a "sigh of relief that the judiciary is still independent in this country". 

The 2014 report on the upgrades to Zuma's residence made clear that he should pay for anything not security-related, in particular the cattle enclosure, amphitheatre, visitor centre, chicken run and swimming pool.

Zuma refused to comply, ordering parallel investigations by the public works and police ministries that largely exonerated him, based on declarations that included calling the swimming pool a fire-fighting reservoir.

In her report, Madonsela said the Treasury and police should work out the "reasonable cost" of the final cost of the five items she deemed non-essential.

Source: Al Jazeera and agencies