The Brazilian state plans some US$11mn worth of works with funds coming from tolls.
President Lenín Moreno held a meeting with the World Bank's representative for the Andean region, Alberto Rodríguez, who said the additional funds will be approved on Friday and the first disbursements will take place in the next few weeks.
The tender is for a contract to build and equip a new children's hospital in Panama City.
The line will be 21km long and have 16 stations. Construction is 77% complete.
Brazil's next administration will need to attract the private sector for infrastructure projects given the government's fiscal challenges, says Alexandre Garcia, an infrastructure analyst at Fitch Ratings.
The Brazilian construction group is in talks with Ashmore to sign up to a bond issue.