The agency says the purchases of bonds were largely moderated by continued reductions in foreign holdings of money market instruments.
It says Canadian investors added $3.8 billion of foreign securities to their holdings in March, following a $4.3 billion acquisition in February.
Foreign investment in Canadian bonds slowed for a second straight month, reaching $5.2 billion in March.
Overall, foreign investors accumulated $25.2 billion of Canadian bonds in the first quarter of 2013.
Foreign portfolio investors sold $600 million worth of Canadian equities in March, following an $11.6 billion reduction in their holdings in February that was largely attributable to merger and acquisition activity.