Culture Secretary Karen Bradley said she is "minded" to order an Ofcom investigation into the planned takeover of Sky by 21st Century Fox.
Competition concerns and broadcasting standards were among the issues of concern, she said.
Ms Bradley has asked for evidence from the two companies and will decide later this month whether to intervene.
Both Sky and Fox are controlled by businessman Rupert Murdoch, who also owns the Times and the Sun newspapers.
A decision to intervene would not block the deal, but trigger an Ofcom assessment as well as a Competition and Markets Authority report to be considered by Ms Bradley.
The Culture Secretary said she had written to the two companies to inform them that she may issue a European Intervention Notice due to "concerns that there may be public interest considerations - as set out in the Enterprise Act 2002 - that are relevant to this proposed merger that warrant further investigation".
The first public interest ground was media plurality and the need for a "sufficient plurality of persons with control of the media enterprises serving audiences in the UK".
Commitment to broadcasting standards was the second ground for possible intervention.
This related to the need for those controlling media enterprises to "have a genuine commitment to attaining broadcasting standards objectives".
Rupert Murdoch's 21st Century Fox said it will pay £11.7bn for the 61% stake in Sky it does not already own.
Sky shareholders will receive £10.75 in cash for each share, valuing the entire company at £18.5bn.