Kobo has suspended all sales of self-published ebooks on its UK site after its rivals were found to have abuse-themed content.
The ereader manufacturer and ebook seller said it wants to "protect the reputation of self-publishing" after Amazon and Barnes & Noble pulled self-published titles containing rape, incest and bestiality content.
Titles which do not offend Kobo's policies will go back on sale in a week's time, the company said, after WHSmith took its website offline to check the self-published books available for purchase.
Kobo provides ebooks for WHSmith, which said it is ensuring its own filters from the Kobo feed are "adequate", while Kobo said it will ensure unsuitable titles did not make their way on to the Kobo platform and then onto WHSmith's website.
The latter's statement said: "We are disgusted by these particular titles, find this unacceptable and we in no way whatsoever condone them.
"It is our policy not to feature titles like those highlighted and we have processes in place to screen them out. We offer over one million titles through our ebooks partner Kobo, many of which are self-published titles.
"Due to the massive amount of self publishing a number of these titles have got through the screening process.
"We are taking immediate steps to have them all removed."
Kobo's director of public relations, Cerys Goodall, added: "Kobo is taking immediate action to resolve this issue which is a direct results of a select few autheros and publishers violating Kobo's content policies.
"We are working hard to get back to business as usual, as quickly as possible."
It denies that it is harming freedom of expression by expunging the titles from its available content.
Last week it was discovered that Amazon's search engine automatically suggested explicit ebooks to users typing apparently innocuous keywords, with no age verification preventing children from finding the texts.
The titles were in the self-published section of the retailers' sites, where authors offer their own work with the site owners taking a percentage of any profit.
The Ministry of Justice has said the sites may have breached the Obscene Publications Act, which is a law requiring publishers to protect consumers from inadvertently finding content which outrages public decency.
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