General view of the explosion area of the pipeline on January 20, 2019 in Tlahuelilpan, Mexico.

Mexico's state oil firm, Pemex, did not close the valve at a leaking gasoline pipeline when first notified because it was not initially thought to be an "important" leak, Mexico's security minister said on Sunday.

The number of people who died from the explosion in central Mexico has risen to 85, Mexico's health minister said on Sunday. An additional 58 people were hospitalized, Health Minister Jorge Alcocer told a news conference.

The explosion took place on Friday, when about 800 people in Hidalgo state's Tlahuelilpan district were collecting fuel from a leak at a major pipeline.

Security Minister Alfonso Durazo told a news conference that Mexico's military detected the leak about four hours before Pemex closed the valve.

— CNBC contributed to this report.