In addition to his role with the BCHR, Mr Rajab is deputy secretary general of the International Federation for Human Rights (FIDH).
Before his imprisonment in July 2012, Mr Rajab was repeatedly detained in connection with the pro-democracy protests that erupted in the Gulf kingdom the previous year.The Bahraini authorities have come under international pressure to release Mr Rajab
Amnesty said that he was punched in the face several times by riot police as he led a demonstration in February 2012, and in May 2012 was charged with "insulting a national institution" in comments about the interior ministry he posted on Twitter.
In June 2012, Rajab was sentenced to three months in jail over different tweets he wrote about the prime minister. The conviction was eventually overturned on appeal, but only after he had begun his two-year sentence for taking part in unauthorised protests.
At his trial, Mr Rajab told the court that he had been held in dire conditions and subjected to ill treatment, including being placed in solitary confinement with a dead animal and kept almost naked.
BCHR's founder, Abdulhadi al-Khawaja, is serving a life sentence for allegedly plotting to overthrow the government. He was convicted on evidence that was widely accepted as having been secured under torture.