Special counsel Robert Mueller has signaled to defense lawyers for Roger Stone, the longtime adviser to Donald Trump, that prosecutors might brandish Stone’s bank records and personal communications going back several years as evidence in the case against him.

Legal analysts said the move could be significant because the sizable amount of potential evidence listed by Mueller – and its nature, in the case of the bank records – seemed to go well beyond the current known charges against Stone.

A court filing by Mueller on Thursday said prosecutors had seized “voluminous and complex” material including “multiple hard drives containing several terabytes of information”, material seized from search warrants executed on “Apple iCloud accounts and email accounts”, “bank and financial records, and the contents of numerous physical devices (eg, cellular phones, computers, and hard drives)”.

Stone was indicted last week on charges of obstructing an investigation, witness tampering and five counts of making false statements. Two of his residences – one in Florida and one in Manhattan – were raided during his arrest.

“It’s interesting that Mueller produced bank and financial records to Roger Stone, given that they don’t appear related to the charges he faces,” former federal prosecutor Renato Mariotti tweeted. “Perhaps Mueller’s team has a practice of producing broad discovery to defendants, but it is not required by the rules.

“If that is not Mueller’s usual practice, perhaps they want Stone to have this information now because there could be additional charges down the line, or because they think his knowledge that they possess this information could encourage him to flip.”

Former federal prosecutor Joyce Vance called the filing “good news for the investigation”.

“This implies that the FBI was able to access communications Stone and others could have assumed were protected from law-enforcement,” Vance tweeted. “This is good news for the investigation, there is no telling what might be in there Stone thought law-enforcement would never be able to see it.”

The indictment of Stone last week suggested that prosecutors might have gained access to encrypted messages sent or received by Stone.

One section of the indictment describes a text message exchange between Stone and an unidentified Trump “supporter” asking about a Stone contact in London alleged to be in communication with the WikiLeaks founder Julian Assange.

“The supporter involved with the Trump Campaign asked STONE via text message if he had ‘hear[d] anymore from London’,” the indictment reads in part. “STONE replied, ‘Yes – want to talk on a secure line – got Whatsapp?’ STONE subsequently told the supporter that more material would be released and that it would be damaging to the Clinton Campaign.”

Stone is suspected of attempting to establish or carrying out back-channel communications between the Trump campaign and Wikileaks – although he has not been charged with any crime along those lines.

He has pleaded not guilty and denied any wrongdoing.