More than 10,000 people have died crossing the Mediterranean to Europe since 2014, the UN said Tuesday, as the EU unveiled fresh plans to stem the migrant flow from Africa.

Following a rash of deadly shipwrecks in recent weeks which claimed the lives of hundreds of people, the UN refugee agency said the number of deaths at sea had risen sharply this year, with a record 2,814 people drowning since January.

And over the past few days, the overall number who have died since the start of 2014 has reached 10,085, the UNHCR said on Tuesday.

With Europe in the grip of its worst migrant crisis since World War II, the rising death toll has prompted urgent efforts to tackle the problem, with Brussels seeking ways to clamp down on the Africa route from after a deal with Ankara in March slashed numbers trying to cross from Turkey.

"We cannot tolerate the loss of life on this scale, we need to do everything to stop it," European Commission vice-president Frans Timmermans said as he unveiled the plans.

The new proposal involves using EU funds to promote private investment of up to 60 billion euros in key countries of origin for migrants, namely Ethiopia, Niger, Nigeria, Mali and Senegal, as well as Jordan and Lebanon, Timmermans said.

Eight billion euros of EU funds are available to support migration deals with external countries, many of which were first mooted at a crisis summit of European and African nations in Malta last year.

The Commission also wants to speed up readmission deals with African countries and with Pakistan and Afghanistan to make it easier to send back migrants who do not win refugee status.

"There will be consequences for those that refuse to cooperate," Dutchman Timmermans told the European Parliament alongside EU foreign policy chief Federica Mogherini.

The European Commission was later to unveil a plan for a "blue card" system for skilled migrants to come to Europe legally.

The aim is to reduce the incentive for people to try to smuggle themselves into the continent illegally on flimsy boats and put their lives at risk.

"If we ever want to compete with the US Green Card, we need an EU Blue Card that deserves the same merit," Migration Commissioner Dimitris Avramopoulos said.

- 'Appalling number of deaths' -
Breaking down the figures, the UN said a total of 3,771 had died at sea in 2015 and 3,500 the year earlier, plus this year's deaths.

"You've now had since the start of 2014 -- when this phenomenon of rising numbers across the Mediterranean happened -- 10,000 deaths," UNHCR spokesman Adrian Edwards said.

"This is clearly an appalling number of deaths that have occurred in the Mediterranean, just on Europe's borders just in the past couple of years," Edwards told AFP.

More than one million migrants and refugees made the journey to Europe in 2015, the majority fleeing war in Syria and the Middle East, and a further 204,000 have come since January, the UNHCR says.

The vast majority have died on crossings between Libya and Italy, as a controversial March deal between the EU and Turkey designed to halt the flow of largely Syrian migrants using the popular Aegean route has led to a sharp drop in arrivals.

The EU's top court meanwhile ruled that countries cannot imprison illegal migrants just for crossing borders in the Schengen passport-free area, in a new blow to efforts to crack down on the crisis.

The ruling came in the case of a Ghanaian woman, Selina Affum, who was jailed by French police at the Channel Tunnel while on a bus from Belgium to Britain using someone else's passport.

The Schengen passport-free area of 26 European countries has come under severe pressure from the migration crisis, with many countries bringing back border controls that were dismantled a decade ago.