"Kudirat Abiola assassinated" was the headline in the National Concord, a newspaper belonging to Mr Abiola, as the family prepared to bury his wife, a 44-year-old businesswoman.
The university in the western city of Ibadan was closed after police had stopped students from leading several thousand people in protest. Fifty students demonstrated against the government at Mr Abiola's sprawling Lagos mansion as preparations began for the afternoon burial.
"Enough is enough, and the government should be ready to kill all of us," said Bopoola Kayode, president of the polytechnic students' union.
Mrs Abiola, the senior of Abiola's several wives, was shot in the head at close range by unidentified gunmen as her car passed along a Lagos street on Tuesday. Her driver was also killed.
National Concord did not speculate further on the killers' motives but exiled members of the main opposition coalition, the National Democratic Coalition, in a statement issued by their London office, also branded Mrs Abiola's murder a political assassination.
Nigeria's military ruler, General Sani Abacha, yesterday sent a letter of condolence to Mr Abiola's family, along with a high-powered delegation led by the chief of army staff, Major General Ishaya Bamaiyi, and including eight government ministers.
The letter said: "It is with great shock that I received the news . . . the federal government will do everything within its power to unravel the mystery of Kudirat's death," the letter said.
Nigeria, Africa's most populous nation with well over100 million people, has been in crisis since former military rulers annulled a June 1993 election deemed to have been won by Mr Abiola. The millionaire businessman has been detained on treason charges in the capital, Abuja, since June 1994 when he proclaimed himself president based on the results of the annulled poll.
Mrs Abiola was a prominent figure in the campaign for an immediate restoration of democracy to secure her husband's release and install him as president.
She had said she last saw him in October 1994.
Hundreds of Muslims in traditional blue mourning robes prayed incessantly at Mr Abiola's home yesterday.
The United States deplored the murder and called on the government to catch and prosecute the killers.
Victims of the upsurge in political violence
Since Nigeria was plunged into crisis by the annulment of the 1993 elections, the number of killings with no apparent motive of theft has risen sharply.
June 1994: A former intelligence chief, Vice-Admiral Babatunde Elegbede, was killed in Nigeria's biggest city, Lagos.
October 1995: Retired politician Alfred Rewane died from a single bullet to the heart. Police blamed armed robbers, despite speculation that the attack might have had other motives.
February 1996: Alex Ibru, the publisher of Nigeria's leading independent newspaper, survived being shot in the head while driving on a Lagos street. A shadowy group claimed responsibility, saying the shooting was to protect the interest of Nigeria's northern rulers.
May 1996: Emmanuel Ikotun, director of administration at the central bank, was shot dead at his Lagos home. A week earlier, he had escaped another attempt on his life. The same month, Rear-Admiral Olu Omotehinwa, a retired naval officer, was killed at his home, also in Lagos.
June 1996: Kudirat Abiola (pictured left) was killed by a gunshot to the head.