LONDON — Rupert Murdoch’s 21st Century Fox said on Thursday that it had reached a deal to take full control of the British satellite television giant Sky, paying about $14.8 billion for the rest of the shares it does not already own.

The formal offer came as Labour politicians here called for Prime Minister Theresa May’s government to review the potential transaction over concerns it would concentrate too much media power in Mr. Murdoch’s hands.

Just over five years ago, 21st Century Fox’s predecessor company, News Corporation, withdrew a $12 billion offer for the rest of Sky — then known as BSkyB — as a firestorm erupted over phone hacking by the news media in Britain.

News Corporation, now a sister company of 21st Century Fox after the two split into separate companies, owns The Sun and The Times of London, as well as The Wall Street Journal. Mr. Murdoch is executive chairman of both companies.