OTTAWA - The mayor of Ottawa says Canada's capital will do everything it can to prevent an attack when it hosts the country's 150th birthday next month but no amount of preparation can guarantee 100 per cent safety.

Mayor Jim Watson is offering that assessment following the latest attack in Britain, on London Bridge, that left seven dead and scores injured.

Justin Trudeau said an unidentified Canadian was one of those killed.

The prime minister said the government would not comment further out of respect for the family of the dead Canadian.

With Ottawa preparing to host one of the largest Canada Day celebrations, Watson says there will be an extra security measures and a noticeable police presence on July 1.

Municipal leaders across Canada observed a moment of silence today in honour of those killed in London at the closing session of a meeting of the Federation of Canadian Municipalities in Ottawa.