Qatar is reported to have filed an official complaint with the World Trade Organization (WTO), aimed at challenging an ongoing trade boycott by Saudi Arabia, Bahrain and United Arab Emirates.
The formal step would mark the first step in the WTO's dispute process.
It means the countries would have to sit down with Qatar to negotiate.
But if a settlement can't be reached within 60 days, the dispute would go to a WTO-appointed panel.
Reuters news agency first reported that the complaint had been filed.
The WTO told the BBC it had not received any information so could not confirm the report.
Saudi Arabia, Bahrain and the United Arab Emirates (UAE) cut ties with their Gulf neighbour on 5 June, saying it supports terrorism. They also gave Qatari citizens 14 days to leave their territory and banned their own citizens from travelling to or residing in Qatar.
Qatar strongly denies the allegation and has rejected a list of conditions for the lifting of sanctions.
Egypt also cut diplomatic ties with Qatar but did not impose restrictions on its 180,000 citizens living there. Yemen, the Maldives and Libya's eastern-based government later followed suit.
In addition, Saudi Arabia, the UAE, Bahrain and Egypt closed their airspace to Qatari aircraft, and said foreign airlines would have to seek permission for flying over Qatar.
The oil-rich state has long practised an ambitious foreign policy with different priorities to its neighbours but there are two key issues which have angered its neighbours in recent years.
One is Qatar's support for Islamist groups. Qatar acknowledges that it has provided assistance to some, such as the Muslim Brotherhood, but denies aiding militant groups linked to al-Qaeda or so-called Islamic State (IS).
The other key issue is Qatar's relations with Iran, with which it shares the world's largest gas field. The Shia Muslim power is Sunni Muslim-ruled Saudi Arabia's main regional rival.
Reproduced under licence from BBC News © 2017 BBC