(CNN) House intelligence committee Chairman Devin Nunes detailed key pieces of his leaks investigation Thursday, arguing that the names of transition officials to President Donald Trump were sought by "Obama-era officials" in intelligence reports.

In a public letter to Director of National Intelligence Dan Coats, Nunes said that he plans to spend August drafting legislation that will help ensure prosecutions of officials who leak classified information.

"All leaks of classified information must be vigorously prosecuted, and the committee is working to ensure law, policy and funding are aligned to maximize the prosecution of these crimes," Nunes wrote.

Nunes also alleged in the letter that "Obama-era officials sought the identities of Trump transition officials within intelligence reports." He made the same charge in March after his clandestine trip to the White House, which ultimately led to him stepping aside from the Russia probe as he himself became the target of an investigation into whether Nunes leaked classified information.

The letter was signed only by Nunes -- no other members of the committee signed onto the request.

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