The Myanmar junta requested permission for "special" flights to land in Thailand and repatriate Myanmar nationals, the Thai foreign ministry said Monday, following clashes in a nearby vital border hub.

Myanmar's civil conflict has stepped up in recent months with forces opposed to the military -- which seized power from a democratically elected government in a 2021 coup -- making gains across the country.

Areas of Myanmar previously untouched by fighting are enduring conflict, with analysts saying the escalation is the biggest threat yet to the junta's regime.

Over the weekend there were local reports of intense fighting by anti-junta groups near Myawaddy town, across the border from the Thai town of Mae Sot.

Myawaddy is the third busiest land crossing, according to the junta's commerce ministry, with some $1.1 billion in goods passing through over the last 12 months.

The Ministry of Foreign Affairs confirmed in a statement that a flight from Myanmar had landed at Mae Sot airport on Sunday, returning the same day, after a request was granted on "humanitarian grounds".

It said the embassy of Myanmar in Bangkok had asked permission on April 6 for three "special" Yangon-Mae Sot flights to transport "passengers and cargo", over the coming three days.

A ministry spokesperson declined to give further details about the flight.

Following the Sunday flight the remaining trips were cancelled, the statement said. It did not give any further details.

Thailand was closely monitoring the situation on the Thai-Myanmar border, and was "ready to take the necessary actions to maintain peace, order and the safety of the people", the statement added.

In a video taken by local media, Thai soldiers can be seen patrolling along the border, some in armored cars, with tents and haphazard temporary shelters seen in the near distance.

Earlier Prime Minister Srettha Thavisin was asked about the flight, telling reporters: "The flight was not about arms transport or military personnel".

He added the plane was only carrying "civilian workers".

AFP was unable to reach a junta spokesperson for comment.