In a setback, a US court has rejected Facebook's claims to block a lawsuit against it in a data breach that affected nearly 30 million users in September last year.

According to a report in Seeking Alpha on Monday, US District Judge William Alsup in San Francisco dismissed Facebook's request, saying claims that Facebook was negligent and failed to secure users' data as promised can go forward, and discovery should move "with alacrity" toward trial.

In September, Facebook admitted that unknown hackers exploited three bugs to steal the personal details of 50 million users -- later adjusted to 30 million.

Turkey's Personal Data Protection Authority has already fined Facebook 1.65 million Turkish liras ($280,000) over data breach. Nearly 300,000 users in Turkey may have been affected by the data breach.

According to the Turkish watchdog, Facebook failed to timely intervene to take proper technical and administrative measures during the 12-day existence of the bug last September.

According to a statement from Facebook in December, the company had discovered a photo API bug that allowed third-party applications to access the photos of Facebook users.

At the time, Facebook said that the bug "might have exposed the non-public photos of 6.8 million users to around 1,500 apps built by 876 developers".

In March this year, Facebook disclosed yet another security incident, admitting to storing hundreds of millions of users' passwords in plaintext, along with plaintext passwords for millions of Instagram accounts.

Facebook is facing a hefty fine from the US Federal Trade Commission over data privacy scandals.

Facebook expects the fine to be in the range of $3-5 billion and has kept aside $3 billion in legal expenses related to the investigation.