UN Secretary-General Antonio Guterres on Thursday appealed for international aid to earthquake-devastated Syria and Turkiye and said relief operations should be depoliticised.

"Now is the hour to stand up for the people of Turkiye and Syria," he said speaking to reporters.

Recalling the welcome refugees have received from both the countries, he said: "I strongly appeal to the international community to show the people of Turkiye and Syria the same kind of support and generosity with which they received, protected and assisted millions of refugees."

While Turkiye has been receiving aid, including from India which has sent personnel relief material on at least six flights, Guterres focused on Syria which is isolated.

Relief operations there face political obstructions because the government of President Bashar al Assad is under western sanctions and most of the quake-hit areas are under rebel control with limited international access.

"It's not the moment to politicise or to divide, but it is obvious that we need massive support," Guterres said.

"The Syria humanitarian fund and the Syria cross-border fund need an urgent injection of support," he said.

He said that he will be launching a "flash appeal" for assistance to Syria.

With the Syrian government under sanctions from several countries, notably the US, Guterres said: "This is a moment in which everybody must make very clear that no sanctions of any kind interfere with relief to the population of Syria."

Most of the areas in northwest Syria hit by the quake are held by rebels, with only one border crossing into the area from Turkiye allowed under Security Council resolutions.

Russia, which supports the Assad government, has been the main obstacle to adding more lines to the Bab al-Hawa crossing in the rebel-held territory, permitting only that crossing in a compromise with the western countries on the Security Council.

"I will be of course very happy if the Security Council could reach a consensus to allow for more crossings to be used, as we need also to increase our capacity to deliver on cross-line operations into Idlib," Guterres said referring to the rebel-held area.

He said that $25 million has been released from the UN emergency relief fund for operations in Syria.

A UN convoy carrying relief supplies crossed into northern Syria through the Bab al-Hawa crossing on Thursday morning, he said.