Former British Prime Minister Gordon Brown, now a United Nations special education envoy, says Syrian refugees have overwhelmed Lebanese public schools, which need more global support.

Brown said Tuesday that Lebanon has made tremendous efforts, enrolling 106,000 Syrian children by introducing double shifts in more than 150 public schools.

Still, Lebanese Education Minister Elias Bou Saab says more than 400,000 Syrian children need schooling, nearly twice the total number of enrolled Lebanese students.

Brown says he will help the Lebanese government raise $100 million before the beginning of the school year in August to expand its enrollment.

Lebanon, a country of 4.5 million, has absorbed nearly 1.2 million refugees since Syria's conflict began in 2011. But the number of Syrians in Lebanon is believed to be much higher.