Mamadou Tandja says the people of Niger want him to stay in power
A call for a general strike in Niger to oppose President Mamadou Tandja's bid for a third term in office has had a muted response in the capital, Niamey.
Security forces are on the streets and many people have stayed at home but there has been little disruption, a BBC correspondent in the city says.
Amid growing tension, Mr Tandja has not travelled to an African Union summit he was due to attend in Libya.
He has suspended the constitution in a bid to stay in power.
His critics have accused him of carrying out a "coup d'etat".
On Tuesday opposition leader Mahamadou Issoufou was arrested and questioned before being released - a day after prominent rights campaigner Marou Amadou was detained.
Last Friday the 71-year-old president announced he would rule the country by decree, and on Monday he scrapped the constitutional court - which had ruled against his proposed law change three times.
The president's opponents called for the whole country to walk out in protest.
The BBC's Idy Baraou, in Niamey, says the strike began as planned on Wednesday morning, and many civil servants and shop owners had stayed away from work.
And he says there is a heavy security presence in the city, particularly around the main market.
But there were still plenty of shops open and there appeared to be more people turning out for work than staying away, our correspondent adds.
Mr Tandja has scheduled a referendum for 4 August on changing the constitution to let him seek a third term in office.
He has already dissolved parliament - new elections are due on 20 August.
Mr Tandja has governed the West African nation since 1999, serving two terms. He is due to step down in December.
His supporters say Mr Tandja has brought economic growth to one of the world's poorest nations and so deserves the right to seek re-election.