BIARRITZ, France - Leaders from the world's seven most industrialized countries started the divided group's 45th summit, clouded by a pile of tough issues with trade tensions high on agenda, on Saturday evening at the French seaside resort Biarritz.

After an informal welcome at the landmark lighthouse overlooking the extremely heavily secured small town, French President Emmanuel Macron and his guests -- Angela Merkel (Germany), Boris Johnson (Britain), Justin Trudeau (Canada), Giuseppe Conte (Italy), Shinzo Abe (Japan) and Donald Trump (the United States) -- will strive to search for common ground amid worsening divergency in next two days.

Tough issues piled on the agenda: tightened trade tensions, trans-Atlantic relations at historical low, climate challenges with unprecedented fires in Amazon rainforest, Brexit with a highly probable scenario of no-deal, Iran nuclear deal at stake, Russia-Europe relations as well as digital taxation dividing not only Brussels and Washington but also members within Europe, just to name a few.

"This meeting is useful, important ... otherwise we would have to divide among ourselves," said Macron in a televised speech earlier in the day.

Conflicts relating "Iran, Syria, Libya, Ukraine and several other international crisis" will be discussed. "Tensions, especially commercial ones, are bad for everyone. We must succeed in reaching a de-escalation, stabilise things and avoid this trade war which is already taking place everywhere," he added.