Europe must urgently set up an effective rescue operation for migrants at sea and commit to receiving significantly higher numbers of refugees, top UN officials and the International Organisation for Migration said.
"A tragedy of epic proportions is unfolding in the Mediterranean," they said in a statement criticising a 10-point plan announced by the European Union on Monday and due to be discussed at a hastily-convened summit later today.
"The European Union response needs to go beyond the present minimalist approach... which focuses primarily on stemming the arrival of migrants and refugees on its shores," it said.
European Union leaders will effectively reverse a cutback in rescue operations the Mediterranean today to try to prevent record numbers of people drowning as they try to flee war and poverty in the Middle East and Africa.
But the joint UN and IOM statement said the funding boost would not make up for the closure of an Italian mission last year after other EU countries refused to pay for it. The mission, Mare Nostrum, saved more than 100,000 lives.
It called for "setting in place a State-led, robust, proactive, and well-resourced search-and-rescue operation, urgently and without delay, with a capacity similar to Mare Nostrum and a clear mission to save lives".
The smaller EU scheme which replaced Mare Nostrum is mainly focused on patrolling the bloc's borders, after countries argued that saving migrants encouraged more to come.
Today's statement was co-signed by the UN refugee boss Antonio Guterres, UN human rights chief Zeid Ra'ad Al Hussein, UN special representative for migration Peter Sutherland and William Lacy Swing, head of the International Organisation for Migration.
It said the safety and human rights of all migrants and refugees seeking to reach Europe's shores should be at the forefront of an EU response that must address the complex factors driving people to flee Africa, Asia and the Middle East.
"Enforcement alone will not solve the issue of irregular migration, but could increase the risks and abuse faced by migrants and refugees," they warned.