The British government warned it will prosecute protesters who break the law if Hezbollah flags are displayed in online demonstrations.
In a change of policy in response to the coronavirus outbreak, the Home Office announced to The National that it will observe protests on Zoom and other online platforms.
Last year Sajid Javid, then home secretary, designated the whole of Hezbollah as a terrorist organisation after its flags were flown at protests in London.
At the Trafalgar Square protest the flag, emblazoned with a Kalashnikov assault rifle, was flown.
Showing support for Hezbollah in the UK carries a maximum sentence of 10 years in jail.
This year’s Al Quds Day event, a pro-Palestinian protest, will be held online on Friday.
The department said it would specifically focus on online protests that have been encouraged by organisers.
Whitehall officials said there had been an “adjustment” in Home Office policy after it said "prosecutions will follow if online protests broke the law.
“There is no place for hatred in our society," it said.
"While peaceful protest is a vital part of any democracy, if protests break the law or incite hatred, whether they are online or in public, there should be no doubt the police will take action.”
The online protest has been organised by a group called the Islamic Human Rights Commission.
It has encouraged people to wave Palestinian flags during the online forum but has not asked them to avoid using the Hezbollah banner.
The Home Office said it did not comment on operational policing but it made it clear that Hezbollah was involved in terrorism after it designated the entire organisation in January this year.
The protest organiser was not a proscribed terrorist organisation so people could express their views at the online meeting, provided they did so within the law.
The Home Office said it was not government policy to comment on whether any group was under consideration for proscription as a terrorist group.
It said that Britain was committed to a free, open and secure internet where users’ fundamental rights were protected.
Al Quds Day protests in Iran, where US and Israeli flags are regularly burnt at mass demonstrations in support of Hezbollah, have been called off because of the virus.
“What can we do at the time of Coronavirus?" the protest organiser said on its website.
"This Al Quds Day, when it is unlikely anyone can go out to protest.
"IHRC and other organisations are calling on you to fly a Palestinian flag in your window or on your car to show your support for the people of Palestine.”
Al Quds Day march in London, held on the last Friday before the end of Ramadan, has been controversial for its signs of support for Hezbollah.
The day was declared in 1979 by Iran’s Ayatollah Khomeini and is marked around the Middle East, the UK and US.
Until the entire organisation was banned last year, the yellow and green Hezbollah flags were legal on London’s streets because protesters could claim they were only showing support for the group’s political wing.
Andrew Rosindell, the Conservative MP who has raised issues about the Muslim Brotherhood targeting vulnerable people online during the pandemic, said he was “very concerned” about the demonstration taking place online.
“The Home Office must step in and take action against any individuals inciting hatred or violence, whether that be in public or online,” Mr Rosindell said.
“Our focus on these terrible demonstrations must not waver simply because they are moving online.”
Alan Mendoza, of the Henry Jackson Society think tank, said the Home Office decision was a welcome development.
“This means that as the conveners of this event, the IHRC, will have to take responsibility for what appears on their online platform,” Mr Mendoza said.
“If an individual displays a banned Hezbollah flag on screen then they should be shut down and evicted from the conversation. Otherwise the organisers will be accessories to a crime.”
“The Home Office clearly understands that criminality during protests can occur online and is reacting to the new truths of what’s happening across the world in this technology-driven coronavirus era."
The IHRC did not respond to a request for comment.