Deputy Assistant Commissioner Sue Akers said the Metropolitan Police was examining claims that one official had received payments totalling almost £35,000 from various newspapers between April 2010 and June 2011.
Another prison officer at a high security establishment had allegedly received payments from Trinity Mirror totalling more than £14,000, the inquiry heard.
But DAC Akers said analysis suggested the journalists had obtained "very limited material of genuine public interest".
Giving evidence to the Leveson Inquiry into press standards for a second time, she said: "It's our assessment that there are reasonable grounds to suspect offences have been committed and that the majority of these stories reveal very limited material of genuine public interest."
The details came as the inquiry was also told how:
• Police were examining whether journalists had accessed information from stolen mobile phones and whether two cases being investigated were the "tip of the iceberg".
• A total of 702 likely victims of phone hacking had now been contacted by police
• 41 people had been arrested as part of Operation Elveden into corrupt payments, including 23 former of current journalists, four police officers, nine public officials and five conduits for payment.
• 15 current or former journalists had been arrested under Operation Weeting into phone hacking.
• Seven arrests had been made as part of Operation Tuleta into allegations of computer hacking and privacy infringement.
Miss Akers explained that detectives were investigating two cases involving allegations that journalists attempted to retrieve information from stolen mobile phones.
She said it appeared one of the mobile phones had been examined with a view to "breaking its security code" so its contents could be downloaded by experts.
She said they were examining whether these were isolated incidents or just the "tip of the iceberg".
During evidence to the Leveson Inquiry in February, DAC Akers, who is due to retire from the Met in May, outlined details of payments of tens of thousands of pounds made by journalists to public officials.
She said the Sun had had a "culture of illegal payments" and claimed £80,000 had been paid to one individual over a number of years, while one journalist had received £150,000 from the paper to pay sources.
Ms Akers agreed to return to give evidence to the inquiry again in September.