Nigerian police have arrested a former government minister who is accused of corruption and who has been an outspoken critic of the current administration.

The State Security Service, or the SSS, detained Malam Nasir El-Rufai Saturday morning at Abuja airport as he returned from a private trip to London. No reason was given for the arrest.

El-Rufai used his mobile telephone to send updates to his twitter feed , saying SSS agents had been “polite and courteous so far” and telling a follower not to worry, that “all will be well.”

His last update before his telephone battery ran out said he had been taken to see the director of the SSS, who had previously worked for him.

El-Rufai served as the Federal Capital Territory Minister under former President Olusegun Obasanjo. He is facing charges of abuse of power and fraudulent allocation of land, but was released in April, pending the trial.

El-Rufai denies the charges. He has become a loud and frequent critic of the government, calling himself on his twitter account a “certified ruffler of feathers.”