Ottawa, Sep 22 The Royal Canadian Mounted Police (RCMP) have launched an investigation after a woman in Quebec province allegedly sent a letter containing ricin poison to US President Donald Trump.

"Our Chemical, Biological, Radiological, Nuclear, Explosives team (CBRNE) is leading the operation," Xinhua news agency quoted the RCMP as saying in a tweet on Monday.

"Police and Fire teams from Longueuil are also on site. All necessary measures have been taken to ensure public safety," it added.

The RCMP further said that a police operation was being carried out at Montreal's suburb of St-Hubert, which authorities said on Monday is linked to the suspect..

Meanwhile the woman was reportedly arrested at the Canadian-US border on Monday and was expected to appear in court in Buffalo, New York, on Tuesday facing federal charges.

Media reports said the letter was intercepted after being sent to Washington from Canada.

Both police and media reports have not yet indicated whether the suspect is Canadian.

Ricin is produced by processing castor beans.

It is a lethal substance that, if swallowed, inhaled or injected, can cause nausea, vomiting, internal bleeding and ultimately organ failure, the BBC reported.

No known antidote exists for ricin.

If a person is exposed to ricin, death can take place within 36 to 72 hours, depending on the dose received, according to the US Centers for Disease Control and Prevention (CDC).

The White House and other federal buildings have been the target of ricin packages in the past.

In 2014, a Mississippi man was sentenced to 25 years in prison for sending letters dusted with
ricin to former President Barack Obama and other officials.

Four years later, a former Navy veteran was charged with sending toxic letters to the Pentagon and White House.

Canadian police probe poison-laced letter sent to Trump