The RNLI has advised volunteers to consider not wearing its branded clothing in certain public areas as they review security measures, after members were targeted online by the far-right.
The charity helped rescue around 120 migrants on Sunday, after they were intercepted near the Isle of Wight, with protests occurring at Eastney Harbour after they were brought to shore.
Protests by masked men had also taken place at Dover the previous day, after another group of migrants were rescued from the Channel.
As a result, certain crew members had their names and photos shared on social media and were accused of “treason”.
The online abuse has been called “wholly unacceptable in a civilised society” by RNLI chief executive Peter Sparkes, who urged people to be “mindful of misinformation”.
Speaking to the BBC, one volunteer who was photographed online, said: “We were there, purely for the safety of the protesters in the water.
“It would be nice for those people who called me a traitor to know that I’m not a traitor.”
Crowds of masked men blocked road access to the Port of Dover on Saturday, followed by official vehicles being damaged and a handful of police officers being injured in a stand-off with protesters overnight on Sunday in Portsmouth.
In a statement issued on Tuesday, Mr Sparkes said: “Recent events have generated deliberate misinformation and a misunderstanding about the RNLI – our purpose, our tasking, and particularly our lifesaving work in the Channel.
“Sadly, as a result, some of our volunteers and staff have been the subject of online and, in the worst cases, physical abuse.
“The RNLI’s people represent the very best in our society, they selflessly give up their time to keep others safe.
“Yet they and their families are being threatened by those who would hide behind a balaclava or a keyboard.
“Their action, in contrast, is wholly unacceptable in a civilised society.
“We will take whatever steps we can, to care for and protect our people and their families.”
A request to land an RNLI boat carrying more than 100 migrants at the Port of Southampton and the Port of Portsmouth was refused on Sunday.
Associated British Ports (ABP), which operates Southampton, said there was not a “safety of life at sea issue where Southampton was the closest port”, and reports have said the King’s Harbour Master (KHM) Portsmouth declined a coastguard request.
Digital secretary Lisa Nandy earlier on Tuesday said she was “personally concerned” about social media doxxing, when a person’s private information is shared online without their consent.
She was responding to Vikki Slade, the Liberal Democrat MP for Mid Dorset and North Poole, who told the Commons that “some very disturbing posts” had emerged on social media, identifying “brave RNLI rescuers”.
Asked what more the Government could do to remove posts “that put children and adults’ safety at risk through doxxing”, Ms Nandy replied: “I have had an initial discussion with some of the tech companies about this.”
She later added: “It is something that the Government is concerned about (and) I’m personally concerned about.”
An RNLI spokesperson said: “Given the unacceptable abuse our people have faced, and with protest activity taking place at RNLI locations, we have taken action to help ensure the safety and wellbeing of our volunteers and staff.
“As well as enhancing security at RNLI locations, we issued guidance to our people earlier this week on how to keep themselves safe.
“This guidance included how to manage potentially challenging interactions with members of the public, and where appropriate, choosing not to wear RNLI branded clothing.
“Our people have been reminded that their safety comes first, and they are encouraged to report relevant incidents internally and, where appropriate, to the police.”
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