In a move designed to coincide with the pope's visit to Britain in September, London buses are to carry posters calling for the ordination of women.

The initiative, from the UK group Catholic Women's Ordination (CWO), will see buses carrying the slogan "Pope Benedict Ordain Women Now".

According to the weekly Catholic magazine the Tablet, CWO has paid about £10,000 for the posters to appear on 10 buses for a month from August 30.

The pope will be in the UK from September 16, spending two days in the capital, and the posters will appear on routes that go past Westminster Cathedral and Westminster Hall. Both venues feature on the papal itinerary.

Last Thursday the Vatican issued sweeping changes to its laws on sexual abuse, extending the period in which charges can be filed against priests in church courts and broadening the use of fast-track procedures to defrock them. But while the document dealt mostly with paedophilia, it also stated that the "attempted ordination of a woman" to the priesthood was one of the most serious crimes in church law.

The mention of both issues in the same breath caused anger within some groups, especially those in favour of women priests, and prompted a Vatican official to clarify its position, saying the crimes were of a different nature and gravity.

The outcry boosted interest in the movement for female Catholic priests, with CWO receiving donations and dozens of membership inquiries.

One member, Pat Brown, said a press conference would be held during the papal visit at which the group would make its case for ordaining women.

"We love the church and don't want to be disruptive. We are trying to get support and would love to have five minutes with the pope. We are very concerned about what is going on in the church at the moment."

Buses have become the preferred vehicle for believers and nonbelievers to promote their cause to the wider public. The trend started in January 2009, when a group of atheists arranged for an "upbeat and positive" message to counter slogans of hellfire and damnation from some churches.

Organisers exceeded their modest £5,500 fundraising target, receiving more than £150,000, and their success encouraged atheist and humanist groups around the world to carry out similar campaigns.

The advert, the idea of writer Ariane Sherine, bore the words "There's probably no God. Now stop worrying and enjoy your life". It was one of the top 10 most complained about adverts of that year.

A parody advert soon followed from the Christian Party, which claimed: "There definitely is a God. So join the Christian Party and enjoy your life".

It drew 1,045 objections, making it the fourth most complained about advert since records at the Advertising Standards Authority began.