The 77th session of the UN General Assembly was declared open by its new President Csaba Korosi.

In his opening remarks on Tuesday, UN Secretary-General Antonio Guterres called for solidarity among member states to address common challenges, reports Xinhua news agency.

The many challenges that defined the 76th session of the General Assembly are still very much around as the new session starts, he said.

"We face a world in peril across our work to advance peace, human rights and sustainable development, from conflicts and climate change to a broken global financial system that is failing developing countries, to poverty, inequality and hunger, to divisions and mistrust.

"Addressing common challenges will require continued solidarity as we demonstrate the great promise and potential of this organization," he added.

The US is the home of cooperation. And the General Assembly is the life within that home. The months ahead will continue testing the strength and durability of the multilateral system this organization represents, he told delegates.

"And the world is looking to the members of the assembly to use all of the tools at your disposal to negotiate and forge consensus and solutions: debate, deliberation, diplomacy. These eternal tools represent the best pathway to a better, more peaceful world."

In his opening remarks, Korosi called for solutions through solidarity, sustainability, and science.

The only way to achieve better outcomes is to transform, he said. "The contours of the transformation we need are already known. The 2030 Agenda for Sustainable Development, the Sendai Framework (for disaster risk reduction), the Paris Agreement (on climate change), and Our Common Agenda (proposed by UN Secretary-General Antonio Guterres ), all point us in the right direction. What remains to be seen is whether we will deliver."

The world is looking to the UN for answers. As the world body's chief deliberative body, the General Assembly bears a special responsibility, he said.

"Having begun my tenure as president, I aim to harness the great talents of this community of member states in forging the systemic solutions needed to transform our world. In accepting this privilege, I vowed to serve as an agent of multilateralism, multiculturalism, and multilingualism," said the president.

"I pledge that impartiality would be the hallmark of our operation. My team and I will do our best to push for 'Solutions Through Solidarity, Sustainability and Science,' the motto I've chosen for this presidency."

He vowed to stand firm on the principles of the UN Charter, which brought member states together 77 years ago and hold them together today.

"Encoded in international law, they (the principles of the UN Charter) provide us with a solid foundation from which to build. From here, I wish to pursue integrated approaches and enhance the role of science in our decision-shaping. I will work to foster measurable progress in the sustainability transformation and cultivate solidarity we need to achieve breakthroughs or to avert further crises and disasters," he said.

He promised to engage closely with the Security Council, the Economic and Social Council, and other relevant UN bodies to further the critical revitalization process, and pursue the ongoing key reforms led by Guterres to make the General Assembly and the United Nations as a whole fit-for-purpose.

The UnS was created out of the ashes of war and destruction, with the intention of being a well of solutions, said Korosi.

"Responding to humanity's most pressing challenges demands that we work together and that we reinvigorate inclusive, networked and effective multilateralism, and focus on what unites us. It is our mission to come together when there are disagreements, and to build bridges when there are deep divides.

"This (General Assembly) hall was created as a place to build trust, to bring about peace and security, development, and human rights. We owe it to our 8 billion constituents -- the people we are here to serve -- to succeed in our aims," he said.

Korosi was sworn in on Monday at the closing of the 76th session of the General Assembly.

Apart from the General Debate, the high-level week will also see a high-level meeting to mark the 30th anniversary of the adoption of the Declaration on the Rights of Persons Belonging to National or Ethnic, Religious and Linguistic Minorities on September 21, and a high-level meeting to commemorate and promote the International Day for the Total Elimination of Nuclear Weapons on September 26.

On September 19, two high-level events convened by UN Secretary-General Guterres -- the Transforming Education Summit and the Sustainable Development Goals Moment -- will be held.

The start of the high-level week coincides with the planned funeral of Queen Elizabeth II, which is scheduled for September 19.

A UN spokesman said he does not anticipate any changes in the schedule of the UN meetings even though many world leaders will be in London on Monday for the funeral.

"There may be impact on the speakers' list of who speaks when. But the meetings are going on as scheduled," said Stephane Dujarric, the chief UN spokesman, on Tuesday.