Family members of prominent Bahraini rights activist Nabeel Rajab say he has been arrested again and could face new charges as he appeals an earlier conviction.

Defense lawyer Jalila al-Sayed confirmed Rajab's arrest on Thursday but says she is not aware of what charges, if any, he will face.

The activist's wife, Sumaya Rajab, says police surrounded their home and ordered her husband to come out. She says they refused to provide a copy of the summons but said the arrest was linked to comments Rajab made on Twitter about the treatment of inmates held at Jaw Prison, where unrest broke out last month.

There was no immediate comment from authorities.

Rajab had been free on bail as he appeals a six-month jail sentence for insulting government ministries on Twitter.