Posters promoting tourism to Israel have been defaced in Cork, Ireland. The adverts, urging people to “Visit Israel”, were placed in bus shelters in the city last week, but a number were vandalised within 24 hours.

Activists placed stickers so that the heading read “Boycott Israel” and the women in the pictures were shown with speech bubbles claiming Israel had stolen Palestinian land and “destroyed more than 500 villages”.

The posters were funded by the Irish4Israel grass-roots campaign group. A spokesman said: “This is no longer just an attack on Israeli tourism advertising; it is also an attack on free speech.”

No group has claimed responsibility for the vandalism, but the Cork Palestina Solidarity Campaign shared images of the defaced posters on its Facebook site with the message: “Let’s make it clear that Cork is against apartheid!”

The slogans were cleaned off the posters, which are due to remain on display until next week.

Meanwhile, anti-Israel activists claim they will launch a major boycott campaign in London this weekend by occupying stores which sell Israeli settlement goods.

The “mystery shopper” mass protest has been planned for two undisclosed central London sites by members of the Palestine Place group.

Organisers have called on supporters to gather at secret locations at 1pm on Saturday to demonstrate against “retailers who profit from the occupation of Palestine”.

In social media posts about the planned action, the activists are encouraged to “be disruptive” and “reclaim the space taken up by settlement goods for education about Palestine”.

The group claims the “swoop” on the businesses will be “one of the most exciting boycott, sanctions and divestments campaign actions in the UK to date”.