Twenty-nine people were injured in the attack on Friday morning.
The UK terror threat level has now been raised to critical – the highest level – meaning an attack may be imminent.
As Jersey sits within the Common Travel Area, the local threat level has also been raised to match that of the UK.
And the States police are to increase security at the Harbour, Airport and other crowded places.
In a statement, the States police said: ‘Following a decision at a Cobra meeting yesterday evening and the announcement of the Prime Minister, the national threat level has been raised to critical – which means an attack is expected imminently.
‘There is no intelligence to suggest that the Channel Islands is a specific target however as we sit within the UK common travel area, the local threat level has consequently also been raised to replicate that of the mainland.
‘In response, armed reassurance patrols will be increased at the island’s port and airport and armed officers may also be seen at other crowded places.
‘Islanders are asked to remain vigilant and to report any suspicious behaviour to the police. However, and to re-iterate, there is no information to suggest that events in London are linked in any way to Jersey.
‘The States of Jersey Police maintain close links with the Counter Terrorism Agencies in the UK and have and will continue to be briefed on a regular basis.’
