ISIS threatens attacks on London in several chilling tweets: Terror police and M15 investigating tweets.

The UK Metropolitan Police have said they are investigating the tweets but do not see them as a "credible threat"

Counter terror police and MI5 are investigating social media bomb threats that appear to come from terrorists in Syria and Iraq.

Chilling warnings of an imminent attack against the UK capital have been made in the past few days on Twitter using the hashtag #LondonAttack.

This chilling picture implied nail and ball-bearing bombs would be used to kill and maim people

The tweeter handles had explicitly warned muslim to stay away from the covent Garden in central London as there were plans to attack civilians there.

Pictures of assault rifles were posted on some accounts, while others apparently showing explosive devices, nails and ball-bearings were uploaded on others.

Threatening with explosives

One so-called Islamic State terror group sympathiser even claimed he had just learned how to make a suicide belt from his older brother.

Last night Whitehall sources said that although the social media alert was being investigated “none” of the bomb threats were thought to be from inside the UK.

Syria: Many of the Tweets are thought to have been sent from accounts in other countries

All accounts that issued the threats have since been taken down twitter

However,The Metropolitan Police has moved quickly to dispel concern about an attack.

A spokeswoman said: "We are aware of #LondonAttack tweets, we're looking into them, we don't now see them as a credible threat."