Counter-terrorism police arrested a man in his 20s after a bomb was sent to a home in north London.
Scotland Yard were called shortly after 9am on Thursday after a resident received a suspicious package in Cricklewood.
Specialist officers attended the scene and found a small improvised explosive device which they worked to make safe. Met Police teamed up with armed officers to arrest a suspect in Cambridge on Saturday morning just after 9am.
He was held on suspicion of attempting to cause an explosion or making or keeping explosives with intent to endanger life or property.
A Met Police spokesman said the man was currently in custody at a south London police station and officers were searching two addresses in Cambridge.
He added: The arrest relates to a suspicious package received via post at a residential address in north London.
Police were called shortly after 9.10am on Thursday to reports of a suspicious package in Cricklewood.
Specialist officers attended and made safe what was assessed to be a small improvised explosive device.
Police confirmed that there was no risk to the local area and enquiries continue.