A council officer has been suspended after "malicious" remarks were posted on social media about the Hillsborough football disaster.
Hartlepool Borough Council confirmed it had been made aware of the tweets about the 1989 tragedy, which claimed the lives of 96 fans.
The posts are said to have included offensive remarks about victims. They have since been deleted.
The authority did not name the member of staff.
Merseyside Police is also investigating.
A council spokesman said: "We have been made aware of a number of malicious social media posts referring to the Hillsborough disaster.
"We view these comments very seriously and an investigation is under way in accordance with council policy and procedure.
"One council officer has been suspended."
Merseyside Police said: "We have been made aware of posts on Twitter making reference to the Hillsborough disaster, and are making enquiries into the matter.
"Merseyside Police would like to remind social media users that any offences committed online, including malicious communications and inappropriate behaviour, can be investigated."