Organisers of an annual anti-Israel march through London next Sunday will not be warning protesters against waving Hezbollah or Hamas flags – because they do not believe it is illegal to do so.

The Islamic Human Rights Commission, a non-governmental organisation, is behind the Al-Quds Day rally, to be held in London on Sunday 3 July, when marchers will protest through the capital, descending on Grosvenor Square.

IHRC chairman Massoud Shadjareh said: “We do not orchestrate all banners or flags and it is up to participants which flag/banner they wish to carry – as long as it is within the law and does not have abusive content or language.”

Asked about previous arrests of those flying Hezbollah flags, the IHRC said: “They were arrested but not charged and this indicates it is not unlawful and no crime was committed.”

The matter was raised with the Home Office last year, after protests during Israeli Prime Minister Benjamin Netanyahu’s visit to London, when two men flying Hezbollah flags were arrested.

Hezbollah has a military wing, which is proscribed as a terrorist group, and a political wing, which is not, so the question of legality has long been unclear.

In October, Assistant Commissioner Patricia Gallen said: “As the flag represents both Hezbollah’s political party and the proscribed terrorist group, displaying it in these circumstances alone does not constitute an offence under Terrorism Legislation.”

However, while two men were initially arrested on suspicion of breach of the peace, police said they were later “further arrested for offenses under Section 13 of the Terrorism Act 2000”. This makes it illegal for someone to “display an article, such as a flag, in such a way or in such circumstances as to arouse reasonable suspicion that they are a member or supporter of a proscribed organisation”.

Protesters have repeatedly circumvented the law by altering a flag in minor ways. This has led to campaigners flying flags similar in appearance to those of extreme groups such as Islamic State, while evading sanction.