Internet security firm Trend Micro on Friday warned that apart from Google’s Gmail service, Hotmail and Yahoo! Mail had also come under attack from cyber criminals.

Senior threat researcher Nart Villeneuve from Trend Micro said that high-profile accounts Hotmail and Yahoo! Mail suffered separate but similar attacks that earlier hit Gmail.

Speaking on the topic, Villeneuve said, “In addition to Gmail, Hotmail and Yahoo! Mail have also been targeted. While the attacks appear to have been separately conducted, these have some significant similarities.”

Earlier on Wednesday, Web search giant admitted that hundreds of Gmail accounts were hacked, including those of senior US officials, journalists, military personnel and officials in a number of Asian countries.

Google further said that the attacks appeared to originate from servers in Jinan, capital of the eastern Chinese province of Shandong.

Secretary Hillary Clinton described the attacks as “very serious,” adding that FBI officials had launched a probe into the attacks.

The main goal of attacks on Hotmail and Yahoo! Mail also appears to allow hackers to secretly read messages from the high-profile accounts.