The Daily Nation's parliamentary Editor John Ngirachu has been released from the Directorate of Criminal Investigations (DCI) headquarters after recording a statement in the presence of his two lawyers.
The editor had been arrested on Tuesday afternoon at Parliament in Nairobi for reporting on procurement by the Interior ministry.
Mr Ngirachu’s reporting was carried in the Nation, East and Central Africa’s largest-circulation daily newspaper.
The reporting was based on the proceedings of the Public Accounts Committee (PAC) of the National Assembly.
Interior Cabinet Secretary Maj-Gen (Rtd) Joseph Nkaissery had said Mr Ngirachu would be released when he reveals the source of the information he used to write his story.
Mr Nkaissery was speaking at a press conference on Tuesday, soon after Mr Ngirachu's arrest.
Mr Ngirachu was held at the DCI headquarters at Mazingira House, off Kiambu Road in Nairobi.
On Thursday, the Cabinet secretary blamed Parliament for releasing confidential information to the media, saying it exposed the government's security capacity and capabilities.
He said his team presented the information to the PAC in camera as provided for in law.
A social media campaign seeking Mr Ngirachu's release, #FreeNgirachu, was on Tuesday evening the top trending topic on Twitter.
Here are some of the tweets Mr Ngirachu posted the day after his article was published.
CONDEMNED THE ARREST
The Media Council of Kenya (MCK) condemned the arrest, saying it was the highest form of impunity displayed by Mr Nkaissery and a "very archaic form of running a public office".
"It's a perpetuation of a weird way of thinking that undermines not only public access to information but freedom of the media as provided for in the Constitution." said MCK's deputy chief executive officer, Mr Victor Bwire.
Cord leader Raila Odinga criticised the arrest and demanded that Mr Ngirachu be freed immediately. He asked Senator James Orengo and lawyer Evan Mwangi to take up the case for free.
The Kenya Parliamentary Journalists Association also demanded Mr Ngirachu's immediate release, calling his arrest an infringement on media freedom.
"We also demand an apology from the police and specifically the Interior Cabinet Secretary Joseph Nkaissery for infringing on the freedom of journalists to cover Parliament," said a statement from the association.