The Athens stock market plunged more than six percent early Monday after last-ditch debt talks collapsed at the weekend, raising fears of a Greek default and exit from the euro.

The Athens Stock Exchange was down 6.57 percent at 0755 GMT after the talks in Brussels between Greece and its international creditors failed, and Greek Prime Minister Alexis Tsipras insisted in an oped piece Monday that Athens would "wait patiently" until the other side became "more realistic".