Facebook last night said that its quarterly profit grew along with its user base as it grapples with concerns ranging from political ads to cryptocurrency. 

The leading social network said its profit topped $6 billion on revenue that climbed 28% to $17.4 billion in the quarter ending on September 30. 

Meanwhile, the number of active monthly users increased by 8% from a year ago to 2.45 billion. 

"We had a good quarter and our community and business continue to grow," said Facebook chief and co-founder Mark Zuckerberg. 

"We are focused on making progress on major social issues and building new experiences that improve people's lives around the world," he added.

Facebook shares rose more than four percent in after-market trades that followed release of the earnings figures, which beat Wall Street expectations.

The California-based company said that costs rose 32% in the quarter, which ended with a headcount of 43,030 employees, an increase of 28% on the same time last year. 

Facebook has been beefing up teams devoted to privacy and security to protect people's data and thwart the kind of voter manipulation campaigns seen during the US election three years ago. 

The earnings release came just hours after Facebook announced it had taken down accounts linked to a Russian ally of President Vladimir Putin seeking to spread disinformation in eight African countries. 

Facebook CEO Mark Zuckerberg has predicted a 'very tough year' for the company

The influence operations hiding behind fake identities were traced back to Yevgeny Prigozhin, who has been indicted in the US in connection with a campaign targeting the 2016 US elections.

"Each of these operations created networks of accounts to mislead others about who they were and what they were doing," Facebook cybersecurity chief Nathaniel Gleicher said in a statement. 

"We're constantly working to detect and stop this type of activity because we don't want our services to be used to manipulate people," he added. 

Facebook came under fresh criticism this week for its hands-off approach to political speech, as a group of employees and US lawmakers called on the social network to fact-check politicians spreading misinformation.

A letter from employees urged the company to crack down on "civic misinformation," saying the spread of debunked claims is a "threat to what FB stands for." 

At the same time, US lawmakers critical of Facebook stepped up their calls for it to revisit its policy, which exempts comments and paid ads on the platform from fact-checking.

This issue has become heated with President Donald Trump's online ads using what some called "provably false" claims.

On an earnings call with analysts, Zuckerberg held firm that it was imperative for Facebook to let political figures speak freely and count on voters to judge truthfulness. 

Facebook makes data public regarding who is behind political ads and how much money is being spent.

Mark Zuckerberg dismissed the notion that Facebook defended political advertising for the money, saying it was likely to account for just a fraction of a percent of revenue in the hot election year ahead.

He has recently faced a torrent of criticism over the Libra cryptocurrency Facebook is seeking to roll out next year. 

"We clearly have not locked down exactly how this is going to work yet," Zuckerberg told members of the US House Financial Service Committee. 

He acknowledged that Libra could be limited to digital payment systems using individual currencies - a less ambitious plan than creating a new coin linked to a basket of major currencies. 

Libra is backed by an alliance of companies in a nonprofit, Swiss-based association, but some lawmakers are skeptical about the project, and want Facebook instead to focus on data privacy. 

While discussing controversies and criticisms heaped on Facebook, Zuckerberg said he expected "this is going to be a very tough year."