Labour is trying to secure cross-party support for an emergency change in the law to prevent News Corporation from renewing its bid to take full ownership of BSkyB.

In a move designed to capitalise on the embarrassment the phone-hacking scandal has heaped on the government, Labour said there was still a possibility that Rupert Murdoch could reopen his bid and the law should be changed to allow ministers to block it. Ivan Lewis, the shadow culture secretary, will introduce a negative motion when parliament returns next week, which – if approved by all parties – could go ahead without a vote.

He has written to the culture secretary, Jeremy Hunt, and the Lib Dem culture spokesman, Don Foster, with his proposals. The aim would be to introduce a new public interest test applicable to media barons to rule people out based on their conduct.

Under Labour's proposed amendments to Section 58 of the Enterprise Act 2002, ministers would be given the necessary powers to ask regulators to apply a wide-ranging public interest test. Ministers would be also be able to intervene at any stage in the process if new information came to light.

Lewis said: "These measures are necessary to ensure that while we wait for the outcome of the Leveson inquiry, no changes in media ownership can occur which are not in the public interest.

"It is essential we learn lessons from the BSkyB fiasco so that media integrity is the top priority when considering future ownership and merger changes.

"Ultimately, there is a strong case for removing politicians from media ownership and merger decisions. But, in the meantime, we must act to address the legal ambiguities which allowed Jeremy Hunt to disregard growing public concern and damaged public trust in the credibility of the decision making process."

In his letter to Hunt, Lewis argued that ministers should be removed from the approval process in the long term, but that while the existing legislation was in place emergency moves were urgently needed to close the loophole that could allow Murdoch to simply bid again for control of BSkyB. The negative motion will be laid in both houses of parliament when they return on 5 September.