World leaders are coming together, virtually, today to mark the 75th anniversary of the United Nations, as the deadly coronavirus pandemic challenges the effectiveness and solidarity of the 193-member world body.

UN Secretary-General Antonio Guterres has deplored the lack of multilateral solutions to global challenges as he opened the summit today.

"No one wants a world government - but we must work together to improve world governance," Mr Guterres said at the UN General Assembly rostrum ahead of virtual speeches by world leaders.

"In an interconnected world, we need a networked multilateralism, in which the United Nations family, international financial institutions, regional organisations, trading blocs and others work together more closely and effectively," Mr Guterres said.

"We also need an inclusive multilateralism, drawing on civil society, cities, businesses, local authorities and young people."

As Covid-19 began to spread around the world, forcing millions of people to shelter at home and dealing a devastating economic blow, countries turned inward and diplomats say the United Nations struggled to assert itself.

The 15-member Security Council took months to back a call by Mr Guterres for a global ceasefire - to allow countries to focus on fighting Covid-19 - due to bickering between the world's biggest powers: China and the United States.

The 193-member General Assembly only adopted an omnibus resolution on a "comprehensive and coordinated response" to the pandemic earlier this month and it was not by consensus.

The United States and Israel voted no.

A $10.3 billion UN appeal to fund fighting the pandemic in vulnerable and low-income countries is only a quarter funded.

Mr Guterres now has taken a lead in pushing to make sure any vaccine for the coronavirus is made available to everyone globally.

A senior European diplomat, speaking on condition of anonymity, said the General Assembly should have acted months ago, but "we were all hampered by, and hit, by the Covid-19".

Higgins addresses UN on anniversary

President Michael D Higgins, addressing the UN event to mark the anniversary, said the UN has been "a forum for advocating and achieving peace" since its foundation.

"The United Nations has not achieved what was for many a peaceful, interdependent world, but we should regularly reflect on what this world might have become, through the abuse of power, had the UN not existed," he said.

"As we meet, the UN remains our best prospect for peace, for united action on issues we share. The UN and its agencies continue to be under attack, be it through underfunding, withdrawal of support, or the often-explicit promotion of a theory of interests by the most powerful as an alternative to the multilateralism which the Charter of the UN demands.

"The United Nations remains the only body through which all nations can work cooperatively to end conflict, eliminate poverty, combat climate change and uphold human rights."

The President said it is an "affront to humanity" in the 21st century, at a time when we have the capacity to abolish human poverty, that we share a planet with hundreds of millions of people who are "locked in avoidable hunger and diseases, deprived of their most fundamental rights, deprived of a dignified existence".

He also spoke strongly about our responsibility around the environment and battling climate change.

"In the last 50 years, we have lost two-thirds of our ecological diversity, a terrible legacy from our generation. Achieving the success of the Sustainable Development Goals is not an option for us anymore, it is the condition for our common survival.

"Our intellectual and ethical capacity is being surrendered. We have resiled to a politics of fear rather than to the emancipatory promise of the politics of possibility.

"We have come to lose not only the discourse of peace so invoked by the UN Charter, but so much of what was universal in its aspiration and implication, including what are the inevitabilities of connections between ecology, economy and society that serve as impediments to our realising a new paradigm of sustained peace and development," he said.

'Moments of disappointment'

The United Nations headquarters is in New York, which was hit hard by the coronavirus.

UN member states had to decide how to work virtually, which they did for several months before resuming some in-person meetings recently.

"We all suffered from the fact that we couldn't meet ... A lot of attention was paid to process more than substance unfortunately," said Mr Guterres.

"I wouldn't put the blame on the UN as an organisation, it's the member states that have to be more assertive and positive."

New York will lack the usual commotion of the annual late September extravaganza of diplomacy, when leaders from around the world and their delegations flood the city.

Instead, each nation has been allowed to send a diplomat from their UN missions to sit in the General Assembly to watch the recorded speeches.

A UN report released today found that six out of ten people believe the United Nations has made the world a better place, but looking ahead three-quarters see the world body as essential in tackling global challenges.

"However, at the same time, over half still see the UN as remote from their lives and say they don't know much about it," the report said.

The one-day special event comes ahead of the annual meeting of world leaders at the United Nations, which starts tomorrow with no presidents or prime ministers physically present in New York.

All statements have been pre-recorded and will be broadcast in the General Assembly hall.

The United Nations was created when countries came together after World War II to prevent another such conflict.

While there has not been another world war, leaders will adopt a statement today acknowledging "moments of disappointment".

"Our world is not yet the world that our founders envisaged 75 years ago. It is plagued by growing inequality, poverty, hunger, armed conflicts, terrorism, insecurity, climate change and pandemics," the statement says.

"All this calls for greater action, not less," it says.