Those affected included Chief Abiola's Concord press, the Abuja Newsday paper, the dailies Sketch and Punch, and the Ogun State Broadcasting Corporation. The police action, carried out late on Thursday, followed an allegation on Tuesday by the Information Secretary, Uche Chukwumerijie, that 'disgruntled politicians have intensified their efforts to take the whole country hostage through increased misuse of sections of the press and the conscious spread of misinformation'.
Most of the media houses were based in south-western Nigeria where the dominant Yoruba people are strong backers of Chief Abiola. They had been sharply critical of President Ibrahim Babangida's decision to cancel the 12 June elections and hold fresh polls, an action that has plunged the country into its worst crisis in a decade.
Abuja Newsday, three of whose staff were arrested, apparently angered the authorities by carrying a report on an alleged relationship between the son of Chief Abiola and General Babangida's daughter.
The clampdown followed several months of temporary detentions and seizures of magazines that have carried scathing reports on the eight-year-old military government and questioned its willingness to step down on 27 August as promised.
Five editors from the weekly magazine The News, which was closed in May and later proscribed, are currently wanted by the security police. They do not sleep at home and suffer constant harassment. Since the closure of The News, the editors have published a new title, Tempo, which they print clandestinely. All 50,000 copies are sold.
'There is really no law that permits the government to stop us from publishing,' said Seye Kehinde, 27, an editor with The News and since its banning, Tempo. 'To the extent that the government itself is not really obeying the laws which it promulgates, we feel we should just go ahead.'
The five editors first clashed with the Babangida government in April last year while they worked for Chief Abiola's weekly African Concord. The police closed the Concord publishing house after the weekly severely criticised the government's performance. Ironically, at the time Chief Abiola demanded that his editor, Bayo Onanuga, apologise to the President. Mr Onanuga resigned instead and was followed by four other editors.
'I said at the time we should give them sleepless nights so that when they wake up in the morning, they should be afraid to open the newspapers,' said Mr Onanuga, the 36-year- old chief editor of The News and Tempo. 'We must keep them on their toes so they know we are really performing the role of a watchdog.'
After leaving Concord, the five formed The News last February. It quickly became combative. They spent a weekend in jail in March after being charged with contempt of court by High Court Justice Moshood Olugbani, whom the magazine had portrayed in an unflattering manner.
Other stories with titles such as 'Help] Nigeria is Dying' earned them regular visits from security agents. On 18 May, a week before its closure, The News issued a joint statement with another critical weekly magazine, TELL, warning that 'as the nation moves laboriously towards 27 August, a conscious policy is afoot to destroy some of the vital pillars of democracy. The press is clearly one of those institutions that can sustain a virile democracy. But now, it is under a fatal assault by a regime that has promised democracy.'
This week's assault on the press has not daunted journalists. 'Society needs certain truths to be told and we should not be afraid to say it,' said Mr Onanuga. 'Journalism should have some sort of social conscious. We should try to sensitise our people so all of us can go forward together.'