US-owned newspaper publisher Newsquest has been barred from buying 10 titles from the Dublin-based Independent News & Media stable.
The Department of Trade and Industry in the UK has said that to allow the purchase to go ahead would be against the "public interest".
The regulator did approve the sale of another 13 titles however, including the Islington Gazette series, the Hackney Gazette, and the Kensington Times.
Competition minister Gerry Sutcliffe said he refused to consent to the transfer of eight Kentish Times titles, including the Bromley and Beckenham Express series and the Gravesend Reporter.
The remaining 10 titles will be the subject of further discussions between the British DTI, Independent Newspapers and Newsquest.
Newsquest is the third-largest regional newspaper publisher in the UK.