Karunanayake this week appeared before a presidential commission of inquiry in connection with the bond sale scandal in 2015.
Perpetual Treasuries Ltd, a subsidiary of a company owned by the son-in-law of Sri Lanka's then-central bank chief Arjuna Mahendran, bought more than half of the controversial bond issue on February 27, 2015, prompting charges of a conflict of interest.
Mahendran and his son-in-law, Arjun Aloysius, have denied any wrongdoing.
A leading civil society think tank, Center for Policy Alternatives (CPA), said, "The allegations are of sufficient gravity to require the immediate resignation of Ravi Karunanayake MP, the Minister of Foreign Affairs."
The CPA says Karunanayake's explanation that he knew nothing of the deal and it was his wife and daughter who had procured the apartment was unacceptable.
"CPA finds the Minster's testimony not only entirely implausible but also deeply damaging," it said.
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