LONDON — Prime Minister David Cameron cut short a state visit to Africa as he confronted a growing scandal over his cozy ties with Rupert Murdoch’s top lieutenants in Britain and the challenge it posed to his year-old government.

Mr. Cameron, the leader of the Conservative Party, agreed to return hurriedly Monday from Africa to hold a special session of Parliament on Wednesday. He did so after coming under renewed assault from a reinvigorated Labour Party, which has repeatedly pressed him to explain in more detail his decision to hire Andy Coulson, the former editor of the now-defunct News of the World, as his communications director.

His close personal ties to Rebekah Brooks, the former head of News International and a confidante of Mr. Murdoch, are also under scrutiny. Both Mr. Coulson and Ms. Brooks have been arrested in a widening probe into hacking the phones of British celebrities, government officials, members of the royal family and victims of high-profile crimes and terrorist attacks.

Beyond the immediate politics, there was a growing sense across the country that the crisis had raised fundamental questions about the culture of collusion between politicians and the press and revealed a deeper malaise in British life that could dominate the national political scene for months or years to come.