The Iranian President said that the USA withdrawal from global agreements is a violation of political ethics and signalled the end of diplomatic solutions.
Sirisena's visit is taking place at the invitation of his Iranian counterpart Hassan Rouhani. He will later leave China for Moscow where he will discuss the Islamic Republic's decision on the nuclear deal with Russian officials.
Iran signed the deal promising to halt its nuclear program in return for the lifting of worldwide sanctions.
Stressing that the nuclear deal proved to the world that Iran is a peace-seeking country, Mr. Rouhani added, "today, we see that the 5 [signatory] countries from Europe and the worldwide community emphasize the implementation of this agreement and insist on its continuation".
The country's foreign minister Mohammad Javad Zarif too is seeking to salvage the deal, this weekend commencing a tour with the other signatories in the hopes the agreement can be "re-designed" without the U.S.
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But when asked again, he replied: "Certainly the deal is not done but obviously there is some interest from our end". As to clarity of whether Wayne is leaving or staying I'll find out when he comes in for training today.
Before announcing America's pull-out from the deal on May 8, President Donald Trump often criticized the agreement and threatened to scrap it unless new, more stringent restrictions were imposed on Iran by May 12.
He also invited Iranian private sector investors to invest in Sri Lanka, and stated: "We have considered good facilities to encourage investors to invest in Sri Lanka to increase our trade and economic relations with other countries, including Iran".
Iran and Sri Lanka also signed a memo on cooperation in cultural, scientific and educational field to increase exchange of knowledge and students between the two sides.
Iran also has a significant influence in Iraq through the Shia-dominated Hashd al-Shaabi militias who have been accused of human rights violations across the country.