A man has been arrested after a Conservative MP was sent abusive messages on Twitter about his stillborn son.
Colchester MP Will Quince received the first communication on Wednesday after he spoke out earlier this week in a row over proposed cuts to maternity services in Cumbria.
One message said the user was "glad his Tory baby is dead".
Police arrested the 40-year-old man on suspicion of malicious communications.
Scotland Yard would not confirm whether the arrest related to Colchester MP Mr Quince's complaint.
A Met Police spokesman said: "Detectives from the Met's parliamentary liaison and investigation team have arrested a man in connection with an ongoing investigation.
"An allegation of malicious communication regarding abuse made via Twitter was reported to police on Thursday, 23 February.
"A 40-year-old man was arrested this morning, Monday, 27 February, on suspicion of malicious communications.
"He remains in custody."