A full-scale alert went out on the Thames to test London’s response to the “highly likely” threat of a terrorist attack.

%image(14927981, type="article-full", alt="'Hostages' aboard pleasure cruiser that's been "hijacked" as part of Thames anti-terrorist exercise")

Some 200 officers took part in the security exercise code-named ‘Exercise Anchor’, to free “hostages” on a pleasure cruiser.

The drill saw a terrorist group hijacking a pleasure boat on the river aimed at “carrying out an attack on central London and taking hostages.

The action mostly unfolded alongside the Blackwall Reach, near the Isle of Dogs, between the Millwall and Royal Docks by the Lea Estuary on Sunday.

“We are ready to respond,” Met Police Commander Harrington said. “This kind of exercise demonstrates that should a terrible event ever happen for real, London is ready for it in the most efficient and effective way possible.

%image(14927982, type="article-full", alt="Police marksmen secure "hijacked" pleasure cruiser to release "hostages" in Sunday's anti-terrorist exercise on the Thames")

“This exercise has undoubtedly helped us to strengthen the working relationship between the other marine agencies that would be involved in dealing with this type of incident on the Thames.”

A Counter-Terror command unit equipped with marine-trained search dogs seized and secured the “hijacked” boat, a borrowed City Cruise pleasure cruiser normally used for trips between Greenwich and Westminster.

Search and rescue teams were deployed to rescue a ‘dummy’ body which had fallen into the river in the midst of the chaos.

The exercise was carried out to test the process of both the emergency services and agencies on river for the first time.

‘Exercise Anchor’ follows on from Lord Harris’s recommendations that security measures on the river be strengthened in his 2016 review of London’s terror attack preparedness.

The terrorism threat level in the UK remains at ‘severe’—meaning that an attack is ‘highly likely’.

The Met Police also ran an anti-terrorist exercise at Canary Wharf late last year to be on ‘ready alert’ should any incident break. Canary Wharf was an IRA target in 1996 when a huge Semtex bomb packed on a lorry was detonated, killing two men and injuring more than 50 other people in March that year.

Suspicious activity can be reported by the public to Scotland Yard’s Anti-Terrorist free phoneline on 0800-789321.