Mr Abiola is charged with declaring himself president of military-ruled Nigeria. He is believed to have won presidential elections that the army scrapped just over a year ago. His detention has sparked political and labour unrest in the country.
In Lagos, three people were killed when police opened fire to break up demonstrations calling for Chief Abiola's release, according to pro-democracy activists. The clashes with police occurred on the first day of a general strike aimed at securing Chief Abiola's freedom.
A member of the National Democratic Coalition, which backs Chief Abiola, said police fired live bullets to disperse protesters in the Oshodi and Festac districts of Lagos.
The general strike, called by the Nigeria Labour Congress (NLC), bolstered a month-old oil workers' stoppage. Lagos, Nigeria's biggest city and commercial capital, was at a standstill as most of its 6 million people stayed at home. Armed police patrolled near-deserted streets and soldiers guarded key installations.
A shipping source said the oil strike had brought oil exports, which earn 90 per cent of Nigeria's foreign exchange, to a virtual halt.