E-book seller Kobo has suspended the sale of all self-published books on its UK website following the discovery of abuse-themed titles.
Kobo - which also makes e-readers - said it did not intend to censor material, but needed to "protect the reputation of self-publishing".
The company said titles that did not violate its policies would go back on sale in a week's time.
Kobo provides e-books for WH Smith, whose site is currently offline.
WH Smith said it was working with Kobo to make sure it was satisfied no similar titles would appear.
"Until we are confident that completely robust screening processes are in place to filter out inappropriate content, our website will not go live," a spokeswoman said.
"For clarity, we are working closely with our eBook partner, Kobo, however we are also ensuring that our own filters from the Kobo feed are adequate.
"We are close to completing our content review and expect the website will be live again shortly."
Kobo said it would undertake a "thorough review" into its processes to make sure unsuitable titles did not make their way on to the Kobo platform, and subsequently the WH Smith website.
Last week it emerged that Amazon, WH Smith, Barnes & Noble, and other retailers were selling pornographic e-books featuring incest, rape and bestiality on their sites.
On Amazon's store, the search function would automatically suggest phrases such as "daddy daughter impregnation".
The Ministry of Justice has indicated that the sites may have breached the Obscene Publications Act, a law that requires publishers to protect shoppers from inadvertently finding content that outrages public decency.
However, it added that since it had received no complaints it would not be investigating further.
Toronto-based Kobo, owned by Japanese firm Rakuten, is a major player in the e-book/reader market. It released a statement on Tuesday explaining the move which does not affect its global store.
"Kobo is taking immediate action to resolve this issue," the company said.
"As a result we are quarantining and reviewing additional titles."
The firm insisted that the move was not censorship, adding that it fully supported "freedom of expression".
"We want to protect the reputation of self-publishing as a whole," a spokeswoman said, adding that the problem was limited to a minority of publishers and authors who had violated content policies.
"While some may find our measures extreme, we are confident that we are taking the necessary measures to ensure the exceptions that have caused this current situation will not have a lasting effect on what is an exciting new channel that connects readers to a wealth of books."
Follow Dave Lee on Twitter @DaveLeeBBC