TAORMINA, Italy, May 26 (Xinhua) -- With an opening ceremony held in the ancient Greek theatre in Italian city of Taormina, the 2017 summit of the Group of Seven (G7) countries kicked off here on Friday.

Italian Prime Minister Paolo Gentiloni welcomed the other six leaders of the world's most industrialized economies, who gather here for two days to talk about terrorism, cyber-security, migration, climate change, inclusive growth, among other issues.

Italy holds the rotating presidency of the group this year, and Gentiloni played host at what is also his first G7 summit as head of the Italian government.

Leaders attending the summit include U.S. President Donald Trump, who's also in his G7 summit debut since his election, Canadian Prime Minister Justin Trudeau, German Chancellor Angela Merkel, French President Emmanuel Macron, British Prime Minister Theresa May, and Prime Minister of Japan Shinzo Abe.

President of the European Commission Jean-Claude Juncker and President of the European Council Donald Tusk are also among the guests.

Representatives from five African nations and six African organizations are also expected to join the G7 on Saturday, the second day of work.

Migration flows and economic development in Africa are in fact among the topics of the summit, and Ethiopia, Nigeria, Kenya, Niger, and Tunisia are the countries invited.

The various delegations comprise some 2,000 people overall, according to the Italian G7 presidency.

Security and counter-terrorism cooperation are key focuses of this summit, which took place in the wake of the bombing attack that killed at least 22 people in the British city of Manchester on Monday.

After the opening ceremony, leaders posed for a group photo, and started their working sessions.

A leisure pause is scheduled in the evening, when G7 leaders enjoy a concert by Milan's renowned Scala Philharmonic Orchestra in the ancient theatre overseeing the bay of Taormina.

A formal dinner with Italian President Sergio Mattarella would follow at one of the hotels within the restricted red-zone, encompassing the whole town perched on a hill some 200 meters above the sea.

Taormina is in lockdown since Monday, and tough security measures and restrictions will remain in force until after the summit closure, with about 9,000 police and military officers deployed in the area.

Tough discussions are expected on some of the issues, especially on trade and climate change, considering President Trump's protectionist tone and his reluctance so far towards the Paris Climate deal.

"Talks will not be simples, but we know the spirit of Taormina can help us to proceed in the right direction," Gentiloni acknowledged on the eve of the summit. He confirmed the G7 would deliver "an important statement on terrorism and security."