South Africa's government has dismissed criticisms that a 215 million rand (£12.8 million) state-funded security upgrade of President Jacob Zuma's private home was extravagant, saying features such as a chicken coop and cattle pen were more than "nice to haves".

The cost of the upgrade has sparked an outcry against Mr Zuma, whose unpopularity as South Africa's leader since 2009 was highlighted when he was booed at a memorial for Nelson Mandela last week.

South Africa's biggest union has called for Zuma to resign over the cost of security at his home, suggesting the scandal could hurt the ruling African National Congress in elections due in April or May next year.

But, after an official investigation into reports of extravagance, the government denied any improper spending on the homestead in Nkandla in the eastern KwaZulu-Natal province.

Public Works Minister Thulas Nxesi justified a new chicken coop and cattle enclosure, saying experts had concluded that roaming cows could damage "sensitive electronic equipment", while free-range chickens were a security risk.