BERLIN — Social media giants including Facebook and Twitter are not doing enough to curb hate speech on their platforms and face fines of up to $53 million if they do not strengthen their efforts to delete illegal posts, a German government minister said on Tuesday.

The move by the country’s authorities comes as technology companies face increasing scrutiny worldwide over how they police online material, including hate speech, potential terrorist propaganda and fake news. The debate has been particularly acute in Germany, which has become a case study for combating such material because of its stringent laws on what can and cannot be published.

For tech companies and free speech campaigners, this global regulatory push could limit how individuals communicate online by restricting people’s digital activities and allowing governments to expand their control over vast swaths of the internet.

Yet for a growing number of policy makers across Europe, the United States and elsewhere, the social media companies have a responsibility to block harmful content from their digital platforms, and must respect national rules that often run counter to Silicon Valley’s efforts to operate across borders.

On Tuesday, Heiko Maas, Germany’s minister of justice and consumer protection, said he would propose a law that would impose stiff fines on tech companies whose social media platforms did not respond swiftly enough to complaints about illegal content. Mr. Maas has been a vocal critic of how such companies treat online content that violates his country’s strict rules on hate speech.

“We must increase the pressure on social networks,” he said in a statement announcing the proposed legislation. (Copies of the proposal were not immediately available for review.)

“This will set binding standards for how companies running social networks must handle complaints and require them to delete criminal content,” he said of the proposal, under which companies could face fines of up to 50 million euros, or $53 million.

The development followed the publication on Tuesday of the results of a study that showed that Facebook and Twitter failed to meet the German target of removing 70 percent of hate speech within 24 hours of being alerted to its presence.

The yearlong study noted that while the two companies eventually had erased nearly all illegal hate speech, Facebook during January and February managed to delete only 39 percent in the window sought by the German authorities and Twitter erased just 1 percent. Google’s YouTube video service fared the best, taking down 90 percent of all content flagged within the 24-hour period.

Since September, the figure for Facebook has fallen by seven percentage points, while Twitter’s takedown rate has not changed. The issue has taken on fresh urgency as Germany gears up for parliamentary elections in the autumn.

Tech companies deny playing fast and loose with national hate speech laws, saying they have taken down illegal material when it has been flagged by users. They also argue, however, that there is a fine line between complying with a country’s rules and outright digital censorship.

“We are doing far more than any other company to try and get on top of hate speech on our platform,” Richard Allen, Facebook’s head of public policy in Europe, said in an interview late last year. “We recognize that this is a work in progress.”

Germany, where it is illegal to promote Nazi ideology or to deny the Holocaust, has been at the center of the debate surrounding what can be published on social media platforms and who is responsible for the content.

Many Germans — among the most engaged users of these services — also remain overtly wary of how much information American tech companies routinely collect about their online activities. Facebook and Google have run into problems with local lawmakers over what can be disseminated on their social networks and on video sites like YouTube.

In response to this criticism and a recent rising tide of hate speech targeting new refugees in Germany, many tech companies agreed to work with the country’s officials in 2015 to remove xenophobic and racist messages from their digital platforms.

“We are disappointed by the results,” said Klaus Gorny, a Facebook spokesman, in a statement on Tuesday referring to the German government study. “We have clear rules against hate speech and work hard to keep it off our platform.”

A spokesman for YouTube said that it was analyzing the proposed legislation and that the video service’s takedown procedures were robust. A representative for Twitter was not immediately available for comment.

The German criticism over how social media companies handle hate speech and other illicit content online is part of a wider global pushback.

In December, a coalition of companies, including Facebook, Google and Microsoft, announced that it had teamed up to fight the spread of terrorist content on the web by sharing technology and information. They also have agreed to a voluntary code of conduct in Europe to fight the spread of online hate speech.

Many of these companies also have been accused of not doing enough to tackle fake news, which became endemic on many social media sites ahead of the United States presidential election in November. With a spate of national elections looming across Europe this year, Facebook and Google have said they will clamp down on false reports shared on their platforms.

“Trust is one of the main assets that social media has,” Andrus Ansip, a European Commission vice president in charge of the region’s digital agenda, said in an interview last month. “If people can’t trust these channels, then they will stop using these platforms.”