PALERMO, Italy Oct 12 (Reuters) - An Italian judge sentenced three men to 20 years each in jail on Wednesday for their role in packing hundreds of migrants into a boat in which 49 suffocated in the Mediterranean last August, a legal source said.

The judge in Catania, Sicily, found the three guilty of murder and facilitating illegal immigration, more than a year after rescuers recovered the victims from the hold of a fishing boat from which they also pulled 312 survivors.

Five others suspected of forming the boat's crew still face trial by a court in Catania, where the victims and survivors were taken by a Norwegian ship after the rescue.

The three convicted, named in a Catania court document seen by Reuters as Mohamed Assayd, Mustapha Saaid and Mohamed Ali Chouchane, were given an accelerated trial.

The source said Assayd is a 19-year-old Libyan, while the latter two are both 24 years old and from Morocco and Tunisia respectively.

Italy is on the front line of a migration crisis which has become increasingly deadly in its third year. Some 90 percent of arrivals began their voyage on smugglers' boats in Libya, European Union officials say.

Last July, another Sicilian court sentenced a Tunisian man to 18 years in jail for contributing to a 2013 shipwreck that killed 366 people. Prosecutors have demanded an 18-year sentence for the man they say captained a boat that sank killing more than 600 migrants in 2015.

At least 142,000 migrants have reached Italy in 2016 and around 3,100 have died making the perilous trip. An estimated 154,000 came to Italy in 2015 and 2,892 died. (Reporting by Wladimiro Pantaleone, writing by Isla Binnie)