Negotiations at the World Trade Organization aimed at clinching deals on food security, fishing and vaccines entered their final hours today after all-night talks.

Some trade sources are hopeful that efforts to circumvent Indian opposition would succeed.

Ministers from more than 100 countries are meeting at the global trade watchdog's headquarters in Geneva this week for the first time in more than four years to thrash out new trade rules - a feat many doubt in an era of high geopolitical tensions.

The body's 164 members must all agree for new global trade rules to be passed, meaning that one member can block deals.

In the June 12-15 meeting, now prolonged until this afternoon, that member has been India.

New Delhi, which has a history of blocking multilateral negotiations, has stuck to long-held demands to maintain subsidies for fisheries and agriculture and pushed for extra carve-outs, trade sources say.

Indian Commerce Minister Piyush Goyal's statements confirmed those demands.

"India is strongly representing its perspective at the WTO to protect the future of every Indian and that of the marginalised," he said on Twitter.

However, some delegates were more upbeat today, including on a package of deals with trade offs possible across the topics.

EU trade commissioner Valdis Dombrovskis said they were "getting closer" in a tweet. WTO deputy director-general Anabel Gonzalez said she was "hopeful".

Negotiators including US Trade Representative Katherine Tai were involved in talks in the so-called 'Green Room' of the WTO most of the night trying to thrash out agreements.

But Tai left early today, a US official confirmed.

Negotiations resumed early this morning and are ongoing with the conclusion due later today, trade sources said.

One of the possible outcomes of the talks is a pared-back version of a deal designed to curb fishing subsidies that caus eover-fishing, a document seen by Reuters showed.

Another is a waiver of intellectual property rights for Covid-19 vaccines and pledges to ease the food security crisis although tussles over the wording continued, sources said.

WTO officials have maintained throughout the meetings that deals can be reached, saying that talks often look hopeless until a final bargain comes together.

Observers expressed frustration with the process.

"The ministerial conference laid bare the increasing dysfunction that inhibits collective action at the WTO," said Jake Colvin, president of the National Foreign Trade Council, adding that members should not reward "obstructionism".