Athens needed to continue its reform path without delay so as to further restore the country's credibility among international creditors and investors, and boost growth, visiting U.S. Treasury Secretary Jack Lew said here on Thursday.

"I look at the progress estimates and I understand how challenging it was for Greece to reform the pension system, as it is also the case for non-performing loans. It is very important that Greece implements the measures agreed for the privatization fund as well as the reforms in the markets and services," Lew said during a press briefing following a meeting with Greek Finance Minister Euclid Tsakalotos, adding the measures would mark a positive cycle for the economy and would kick-start the Greek debt discussion.

For his part, Tsakalotos referred to the May 24 Eurogroup statement which acknowledged the Greek debt load was not sustainable and underlined "now we are discussing the technical details, and not whether debt relief is needed."

According to the Greek official, the talks at the finance ministry and prime minister's office on Thursday also included the impact of Brexit and developments in Turkey following last Friday's failed military coup.