Security forces in Sudan have arrested a prominent opposition politician, his wife and a party official said on Sunday.
The arrest comes just days after the country's main opposition parties called for strikes and protests to topple the government.
The Arab-African country avoided the sort of mass unrest that overthrew rulers in Egypt and Tunisia in 2011, but small anti-government demonstrations have broken out over the last three weeks, driven by rising anger over austerity measures.
Authorities have swiftly put the protests down, using police and teargas.
Security agents arrived at the house of Kamal Omar, a prominent member of the opposition Popular Congress Party, at around 11:00pm (2000 GMT) on Saturday night and arrested him, his wife said.
"Two cars came to our house and about five security officers came inside," she told Reuters.
Another party leader confirmed the arrest. There was no immediate comment from the security services.
The arrest followed a declaration on Wednesday signed by the country's main opposition parties that backed the demonstrations, even though they have not yet brought their supporters onto the streets in large numbers.
Omar's party is headed by Hassan al-Turabi, once one of Sudan's most influential politicians and a former spiritual mentor to President Omar Hassan al-Bashir, who came to power in a bloodless 1989 coup. Turabi himself has been arrested a number of times.
The two men fell out in the late 1990s and Turabi has since become one of the government's most outspoken critics.
Sudan has been battling an economic crisis - including a budget deficit, high inflation and a depreciating currency - since South Sudan took three-quarters of the country's oil production with it when it seceded a year ago.
Oil was previously Sudan's main source of state revenues and foreign currency.