The EU on Friday used new regulatory powers to query Meta about ad-free subscriptions to Facebook and Instagram as well as claims some voices are suppressed online in a phenomenon known as "shadow banning".

The European Commission made a request for information under the mammoth content moderation law known as the Digital Services Act (DSA), which came into force last August for online giants like Meta.

The EU's executive arm has launched a wave of probes under the DSA to quiz platforms on how they are addressing concerns from consumer protection to children's activity online.

The latest request is a first step in a possible compliance procedure, but does not itself suggest there have been breaches of the law or a move towards punishment.

The commission wants more information about Meta's offer from November for Facebook and Instagram users in Europe to pay monthly subscriptions to use the platforms without adverts and without their data being tracked for targeted advertising.

Privacy and consumer rights campaigners have slammed the subscriptions, and filed separate formal complaints with data protection authorities.

Now the commission wants Meta to give "additional information on the measures it has taken to comply with its obligations concerning Facebook and Instagram's advertising practices, recommender systems and risk assessments" related to subscriptions.

Recommender algorithms are used by platforms to push more personalised content. Under the DSA, platforms must mitigate risks arising from such systems as well as offer users a non-personalised feed that does not rely on "profiling".

Brussels also demanded Meta "provide information related to the practice of so-called shadow banning and the launch of Threads", a spin-off of the Instagram photo app.

Individuals, including politicians, and groups accuse some media platforms of shadow banning -- or actively limiting the reach of certain viewpoints, including conservative opinions.

Since the outbreak of war in Gaza in October, there have been accusations against platforms, including Facebook and Instagram, of censoring pro-Palestinian voices in particular.

The platforms have firmly denied such claims.

Meta must respond to the EU's questions by March 22.

"The DSA mandates transparency around 'shadow banning' and similar content moderation", such as deletion and suspension, a commission spokesperson said.

"In some cases, such practices could have a bearing on the societal risks that (large platforms) need to identify and mitigate," the spokesperson added.

For example, if a user has been "moderated", the largest platforms need to give a "very comprehensive" explanation for why such a decision has been taken.

The EU's request comes after Instagram last month said it would not "proactively recommend content about politics" on users' Instagram and Threads recommended feeds.

Meta has taken similar steps to reduce the amount of political content on Facebook. (AFP)