Scotland Yard has also circulated images of two of the packages to sorting offices and transport workers in the capital — and other regional forces are also on high alert, ONA reports citing Sputnik.
A "suspicious item" has been found at Parliament and is being investigated by the police.
Specialist officers assessed the item found near the House of Lords and deemed it "non-suspicious".
The news comes just hours after a controlled explosion was carried out on a suspicious package found at the University of Glasgow.
Assistant Chief Constable Steve Johnson said that package had been received at the university earlier on Wednesday, 6 March.
It was not opened and there were no injuries to university staff or students but several buildings were evacuated as a precaution, he said.
Staff at transport hubs across Britain are told to "be vigilant" as police investigate packages containing improvised explosive devices were sent to three major London transport hubs 5 March, in what may have been an "Irish dissident plot".