Manama: An opposition leader jailed in Bahrain is gravely ill and prison authorities have not provided him with proper treatment, relatives said on Friday.

Hassan Mesheima's son Mohammad told the Associated Press his father was treated for cancer before he was jailed in March for his role in anti-government protests this year. He said his father told him the cancer has returned and that he needed more treatment. Mesheima's family asked authorities to facilitate it, but "our efforts were rejected", his son said in a phone interview.

Mesheima and seven other opposition leaders were convicted in June by a special security court of trying to overthrow Bahrain's rulers and sentenced to life in prison.

Bahrain's Information Authority denied allegations that Mesheima's health was deteriorating and said the 64-year-old opposition figure was not being mistreated in prison.

Tried in absentia

"The government can confirm that there has been no recurrence of cancer, according to [Mesheima's] medical records and an extensive checkup which occurred only 22 days ago," the Information Authority said in an e-mailed statement on Friday.

Last year, while Mesheima was in self-exile in London and receiving cancer treatment, he was tried in absentia along with 24 other activists accused of plotting to overthrow the government.

Bahrain's leaders dropped the case in February at the height of the anti-government protests. Many observers saw that as an attempt by the government to ease the pressure of street marches. Mesheima then returned to the country and was arrested.