(Note: election law forbids publication of polls in Peru a week prior to April 10 voting)
LIMA, April 8 (Reuters) - A Datum poll shows left-wing candidate Ollanta Humala winning the first round of Peru's presidential election on Sunday with 31.9 percent of the vote, followed by rightist lawmaker Keiko Fujimori with 22.3 percent, a source with access to the poll said on Friday.
The poll, carried out between April 5 and April 7 among 5,002 people, gave former Prime Minister Pedro Pablo Kuczynski 17.3 percent and former President Alejandro Toledo 15.3 percent, the source said on condition of anonymity. The poll has a margin of error of 1.4 percentage points.
Such an outcome on Sunday would pitch Humala and Fujimori in a June 5 run-off.
Reporting by Patricia Velez; Writing by Helen Popper,Editing by Sandra Maler