Harare - A pastor who prophesied that President Robert Mugabe would die on October 17 was arrested in Harare on Monday, his lawyer said.Patrick Mugadza has been told he undermined the authority of the longtime Zimbabwean leader, who turns 93 next month. He was later charged with criminal nuisance, according to the Zimbabwe Lawyers for Human Rights.The pastor made the prophecy last week.Mugadza first came to prominence in December 2015 when he was arrested for staging a one-man protest against Mugabe in Victoria Falls.Gift Mtisi of Zimbabwe Lawyers for Human Rights said: "He was arrested on charges of undermining the authority of the president.""They are claiming he made a public statement – I think at a press conference – that President Robert Mugabe would die on 17 October  unless he prays."He says it’s not an offence [because] he just conveyed God’s message, a prophetic message. Upon arrest he was told of the charge but he hasn’t been formally charged."Mugabe's health is a regular subject for speculation in Zimbabwe.Mugadza is understood to have been arrested at a court in the capital where he was due to go on trial for wearing Zimbabwe's national flag without permission in November last year. Anti-government protesters last year turned the Zimbabwe flag into a symbol of opposition to Mugabe's long rule. The pastor draped his over his shoulders. Prosecutors said he "disrespected" the national symbol.