Twitter has threatened to sue Meta for launching Threads, which aims to rival Elon Musk's social network and has already attracted tens of millions of users, despite its recent launch.

In a letter to Meta CEO Mark Zuckerberg, lawyer Alex Spiro, representing Twitter, accused the company of using Twitter's trade secrets and other intellectual property by hiring former Twitter employees to create an app that mimics the social network.

According to a report published today by Lusa, the decision further heightens tensions between the two social media conglomerates after Threads began operating on Wednesday, in the context of the unpopular changes Musk has made to Twitter since buying the platform last year for 44 billion dollars.

In reaction to Spiro's letter, Meta spokesman Andy Stone wrote today, exactly at Threads: "No one on the Threads engineering team is a former Twitter employee - there's no such thing."

In the letter, which the news site Semafor published on Thursday, Spiro assured that Twitter "strictly seeks to guarantee its intellectual property rights" and stressed the company's right to seek a solution through civil proceedings or a court order. He added that the letter marks a "formal communication" to Meta to preserve documents relevant to a potential dispute between the companies.

In response to a message on Twitter about the possibility of legal action against Meta, Musk wrote: "Competition is good, cheating is not".

Some analysts have considered that Meta's new product, presented as a text version of the photo-sharing app Instagram, could be a concern for Twitter - pointing to the excitement surrounding its launch and the impressive number of sign-ups already made. But success is not guaranteed. Industry observers cite Meta's record of launching stand-alone apps that are then shut down and point out that Threads is in its early days.

Among other problems detected, the new Meta application has raised concerns about information privacy. Although it has been launched in more than 100 countries, it is unavailable in the European Union, precisely because of the strict privacy rules in place there.

Zuckerberg announced today that Threads has already attracted 70 million users: "70 million Threads sign-ups at the end of this morning. Way above our expectations," he wrote on his Threads account. Meta, which owns Instagram, Facebook and WhatsaApp, made Threads available to the public ahead of schedule, at midnight on Wednesday.

Its proximity to Instagram has contributed to its strong growth. In any case, observers point out that Instagram has two billion users worldwide and Twitter 450 million, so it's still early days for Threads to claim victory.