A Zimbabwean pastor leading a campaign against the government's handling of the economy has reportedly been charged with inciting public violence.
His own #ThisFlag Twitter campaign feed and the state-run Herald paper tweeted that Evan Mawarire was also being charged with disturbing the peace.
Activists organised a "stay-at-home" protest last Wednesday and planned similar shutdowns this week.
It has mostly been organised on social media and WhatsApp using #ThisFlag.
Zimbabwe's economic crisis has worsened recently, leading to a chronic cash shortage and delays paying civil servants.
Pastor Mawarire was summoned for questioning by police ahead of a two-day "stay-at-home" protest called for Wednesday and Thursday.
Several hours after he reported to the Criminal Investigation Department (CID) on Tuesday morning, the #ThisFlag Twitter account posted: "Pastor Evan Mawarire is being charged with section 36 for inciting public violence and disturbing peace."
It included a video in which the preacher says: "You are watching this video because I have either been arrested or have been abducted. It's a video we had pre-recorded for a day like this one."
He ends his message saying that he hopes the shutdowns have been successful.
"Hold this government to account. Never let them get away with anything," he says.
"Remember this flag is our flag, no-one else loves Zimbabwe more than a Zimbabwean."
Import ban anger
According to Zimbabwe's private Newsday newspaper, the pastor turned up at the central police station in the capital, Harare, with a bible and a Zimbabwean flag but without his mobile phone, which is what sources at the station say the CID wants access to.
The authorities have been trying to trace who has been sending out messages about the national shutdown, as several activist groups have been involved.
Last Wednesday's stay away led to a complete shutdown of schools, businesses and shops across the country.
It was the biggest strike action since 2005 and public transport and some government departments, including the courts, also ceased to function.
Last week, taxi drivers complaining about police extortion also clashed with the security forces in parts of Harare.
Civil servants who had not received their June salaries were paid in the wake of the strike.
These have to be paid in foreign currency as Zimbabwe abandoned its own currency in 2009 in order to stem runaway inflation.
There is also anger at a government ban on importing many goods which has been implemented in order to save scarce foreign currency.
But with unemployment at more than 90%, many Zimbabweans rely on cross-border trading to make a living.