British-Iranian citizen Nazanin Zaghari-Ratcliffe, who is serving a five-year jail sentence in Tehran for alleged sedition, could be due for early release and possibly home for Christmas, her husband said Thursday.

Richard Ratcliffe told AFP that his wife had received notification from her Iranian lawyer that she was now "marked for early release" following an update on Iran's judicial database.

"I'm reasonably positive. It's not clear how good the news is, but it's definitely good news," he said.

"It's like it's moved another stage. He (lawyer) said there's still paperwork to finalise, but it should be over soon -- days to weeks, not months or years."

On being home by Christmas, he said there was "an outside shot".

"We're not there yet but the tunnel feels a bit shorter."

British Foreign Secretary Boris Johnson lobbied for Zaghari-Ratcliffe's release on humanitarian grounds during a trip to Iran earlier this month.

Zaghari-Ratcliffe, who works for the Thomson Reuters Foundation, is serving five years for taking part in mass protests in 2009, which she denies.

Tulip Siddiq, her constituency MP in Britain, called the news a "glimmer of hope".

"It has given Nazanin a real boost of positive energy, and now we wait impatiently to see what happens next," she said, after speaking to Richard Ratcliffe.

"Although we do not want to celebrate prematurely, it would be the perfect Christmas gift to see Nazanin released and back with her family where she belongs."

Zaghari-Ratcliffe was arrested at Tehran airport on April 3, 2016, after visiting relatives with her young daughter.

Johnson was accused of jeopardising her defence by saying she was training journalists before she was arrested -- something the Thomson Reuters Foundation and her family have strongly denied.

An online petition for her release has collected almost 1.5 million signatures.