"Praise Allah" will adorn hundreds of buses across the UK as part of a campaign by an Islamic charity to help victims of Syria's civil war.

Islamic Relief, Britain's biggest Muslim charity, will run the campaign during Ramadan next month, when Muslims fast during daylight hours and give money to charity. The posters will appear on buses in London, Manchester, Leicester, Birmingham and Bradford.

The charity said it hoped the posters would help show Islam and Islamic aid in a positive light.

Imran Madden, the UK director of Islamic Relief, said: "In a sense this could be called a climate change campaign because we want to change the negative climate around international aid and around the Muslim community in this country.

"International aid has helped halve the number of people living in extreme poverty in the past 15 years, and British Muslims are an incredibly generous community who give over £100 million to international aid charities in Ramadan."

Half of Britain's Muslims live in London where Sadiq Khan has become to capital's first Muslim mayor. Transport for London, for which Khan now has responsibility, bans adverts linked to a "political party or political cause" but does not ban religious advertising.

However former Mayor of London Boris Johnson intervened in 2014 and banned an advert from a Christian charity which suggested people could "get over" homosexuality. The ban was upheld in the High Court after an appeal and Core Issues Trust were fined £100,000 in legal costs.

In 2009 a group of Christian charities responded to an advertising campaign by the British Humanist Association that read: "There is probably no God. Now stop worrying and enjoy your life."

The Trinitarian Bible Society, the Christian Party and the Russian Orthodox Church followed with a bus advert on 175 London buses that read: "There definitely is a God. So join the Christian Party and enjoy your life."

Simon Calvert, deputy director of public policy at The Christian Institute, said he hoped Islamic Relief's advert "signals the beginning of a new era of greater expressions of the Christian faith, which seems to have become persona non grata".

He said: "People were surprised by the cinema advertising agenda to ban the Lord's Prayer – something we all grew up with.

"Audiences are capable of hearing expressions of Christian faith without running away screaming in horror."