Nigerian police have detained a journalist for refusing to disclose the source of a story about last week's takeover of parliament by security agents, his employers said on Wednesday. Samuel Ogundipe, a reporter with the independent online newspaper Premium Times was arrested with two colleagues on Tuesday and detained at the Special Anti-Robbery Squad (SARS) in Abuja, the capital. Ogundipe's colleagues were later released after questioning. Premium Times said Ogundipe was being held for publishing a report sent to acting president Yemi Osinbajo by the inspector general of police, Ibrahim Idris, on events that took place at the National Assembly on August 7.* Sign up to News24's top Africa news in your inbox: SUBSCRIBE TO THE HELLO AFRICA NEWSLETTERFOLLOW News24 Africa on Twitter and Facebook. Hooded operatives of the State Security Service (SSS) blocked access to the Senate and House of Representatives, preventing lawmakers from entering workers, journalists and other visitors from entering.The reason for the operation remains unclear. Independent sources speculate it was a show of strength connected to a political crisis ahead of presidential and parliamentary elections next February."They repeatedly asked the journalist to disclose his source for a story published by this newspaper," Premium Times said in a statement. The paper condemned the "clampdown on a law-abiding citizen and journalist with an apparent sinister view to inhibiting the practice of his profession." It said the "subterfuge employed in bringing in the reporter, even while harassing his colleagues should also be condemned by all Nigerians." The police were not immediately available for comment. The Nigeria Union of Journalists (NUJ) also condemned the detention while calling for the immediate release of the reporter. "The NUJ is horrified by the constant harassment and molestation of journalists by the police and other agents of the state and requests that such should abate forthwith," NUJ President Waheed Odusile told AFP. "It should be noted that confidentiality of sources is necessary for good journalism to flourish and journalists should not be coerced into revealing such sources," he said. "We call for the immediate and unconditional release of Ogundipe and an end to all forms of impunity against the media." His detention came on the same day the vice president ordered an overhaul of the police special anti-robbery squad following complaints about abuses, extortion, torture and extra-judicial executions by its operatives. Osinbajo - standing in for President Muhammadu Buhari who is on holiday - last week fired the head of the intelligence service, which oversees the SSS, after the brief takeover.