Francis Matthew, editor-at-large of Gulf News, was arrested after his wife Jane Matthew, 62, died on 4 July.
The Government of Dubai's media office said preliminary investigations showed she died from a blow to the head with a solid object.
The Foreign Office said support is being provided to Mrs Matthew's family.
"We are also providing support to a British national detained in Dubai," a spokesman added.
The media office said on Twitter that Mr Matthew had told police he assaulted his wife and threw a hammer at her, without intending to kill her.
Abdul Hamid Ahmad, editor-in-chief of Gulf News, said in a statement: "We are shocked and saddened at this tragedy.
"Francis was editor of the paper from 1995-2005.
"He is a well-respected journalist, known for his keen insight into the Middle East. He was holding the position of editor-at-large at the time of the incident.
"Both Francis and Jane have played a very active role in the British expatriate community over the past 30 years."
Investigations by Dubai police are continuing.
A British journalist at a newspaper in Dubai has been charged with murdering his wife, the emirate's government says.