The multitude of migration crises facing the world are symptoms of a long line of brutal conflicts and rights violations, the UN rights chief said Monday.

"Political turbulence, repression, violence and war have become so widespread that they impel many millions of the world's people to risk their lives to find a place of relative safety," said Zeid Ra'ad Al Hussein.

"Migration is the symptom, the cause is despair, after repeated human rights violations have stripped an individual of all hope of justice and dignity," he told the opening of the UN Human Rights Council's June session.

The UN's top rights body was set to have a lengthy discussion on the rights of migrants later Monday.

"Your leadership on this issue will be vital, particularly in terms of the multiple crises regarding migrants en route to Europe Southeast Asia and Australia, Zeid told the diplomats in the room.

His comments came as surging numbers of migrants and refugees have been risking their lives on rickety boats to reach safety in different parts of the world.

More than 100,000 people have made the perilous journey across the Mediterranean to Europe so far this year, and some 1,800 have drowned trying.

Southeast Asia's migrant crisis meanwhile unfurled at the start of May, leaving thousands from Bangladesh and Myanmar's persecuted Rohingya minority trapped at sea.

Since then, around 4,500 of them have returned to shore, but the UN estimates around 2,000 others are still on the water.

PROBE VIOLATIONS AGAINST ROHINGYA

"I am particularly concerned about the persecution of the Rohingya community in Myanmar," Zeid said, adding: "I believe the time has come for the Human Rights Council to probe more deeply into the nature and scope of these violations, and how they might more effectively be addressed."

Myanmar refuses to recognise the majority of its Rohingya as citizens and places a raft of restrictions on them, such as family size, movements and access to jobs.

In recent years tens of thousands of Rohingya have left, fleeing on often deadly voyages across the Bay of Bengal at the hands of ruthless people-smuggling and trafficking networks.

Many diplomats also voiced concern about the surging waves of desperate people risking their lives to reach safety.

"The increase in migration flows, smuggling and trafficking of human beings, and the associated human rights abuses are global phenomena of rising concern," Latvian ambassador Raimonds Jansons said on behalf of the European Union, which requested the pending debate on the issue.

"We must deal better with the root causes of migration," he told the council.

Bangladeshi ambassador Shameem Ahsan also lamented the "current grave situation involving migrants," and demanded "a holistic approach ... emphasising on the root causes."