A man in his 50s was arrested in connection with the blaze at the South African parliament caused extensive damage on Sunday.
Public Works and Infrastructure Minister Patricia De Lille told reporters, adding that the case had been handed over to an elite police unit called the Hawks.
"It's the role of the Hawks to investigate any attack on political institutions," De Lille said.
There were no reports of any injuries.
The fire broke out in the early morning and authorities said the sprinkler system appeared to have been tampered with and so did not work. By afternoon, firefighters were still trying to contain the blaze in one of the several buildings that make up the parliament complex in the legislative capital, Cape Town.
The cause of the blaze was not yet known but De Lille said that according to a report that she received, a standard maintenance fire drill had been conducted just before parliament closed for the Christmas and New Year holidays and everything including the sprinklers was working.
"What was discovered this morning is that somebody has closed one of the valves and so then there was no water to trigger that automatic sprinkler system coming on," De Lille said, adding that CCTV footage confirmed that somebody was in the building from the early hours of the morning.
President Cyril Ramaphosa told reporters after visiting the site that parliament's work would continue despite the blaze. He also praised firefighters for saving a "very important national asset of our government".


Trump to pause attacks on Iran's energy plants
No injuries reported as Kuwait Shuwaikh Port comes under drone attack
IRGC-linked cells targeting Bahrain referred to Criminal Court
Trump says Iran's 'present' to US was allowing 10 oil tankers through Hormuz
EU agrees to fine online platforms importing unsafe products
Iran sees US peace plan as 'one-sided' as Trump presses for deal
Ukraine's Zelenskyy arrives in Saudi Arabia for 'important meetings'
US jury verdicts against Meta, Google tee up fight over tech liability shield
