The Philippines has launched a survey on the number of overseas Filipino workers (OFWs), a major contributor of the country's foreign exchange, a state agency said Thursday.

The National Statistical Coordination Board (NSCB) said that the Survey on Overseas Filipinos (SOF) aims to gather information on the number of Filipino citizens who leave the country to seek work abroad, their remittances (cash and in-kind), mode of remittances, their occupation and place of work abroad.

"In light of this, the public is encouraged to participate in the survey," said the NSCB, adding that the government has earmarked 10 million pesos ($232,558) to cover around 50,000 households nationwide.

It noted that in the 2012 SOF, there were about 2.2 million OFWs in the country, 95 percent of whom were overseas contract workers or those with existing contracts abroad. More than half of them were male OFWs and one in every three OFWs was a laborer or an unskilled worker.

OFW remittances are the largest source of foreign exchange income in the Philippines. The government estimates the number of OFWs at 10 million, accounting for one tenth of the country's population.