The Philippines recorded a net outflow of foreign funds in April, reflecting investor jitters over an impending leadership change, the chief investment officer of the country's largest bank said Tuesday.

Davao City Mayor Rodrigo Duterte and Sen. Grace Poe, the two frontrunners in the May 9 elections, are the "biggest risk" because they are "really unknown" to foreign fund managers, said BDO Unibank's Frederico Rafael Ocampo.

The net outflow in April was "glaring" because the Philippines was tipped for robust growth this year and other emerging markets such as India and Indonesia posted net inflows during the same period.

"There are jitters as we've seen in April, from a net inflow in March we reversed to a net outflow," Ocampo told ANC's "Market Edge with Cathy Yang."

"That reflects the jitters. He (Duterte) is a relatively unknown entity. They have to see if his tough words are matched with tough action," said Ocampo, who is also a senior vice president at BDO.

The first test for Duterte or Poe, if elected, would be to appoint a competent economic team, Ocampo said.

Ocampo said the Philippine Stock Exchange Index (PSEI) was expected to trade within a tight range of 7,150 to 7,300 points in the run-up to May 9 as investors stay largely on the sidelines.

"Political risk now is on its way up as we head to e-day (election day) and with the very tight election expect it to go down the wire," he said.

Duterte widened his lead over erstwhile frontrunner Poe to 12 points in the April 12 to 17 survey by ABS-CBN and Pulse Asia. It was the widest margin so far in what started as a tight four-way race that included administration bet Mar Roxas and Vice President Jejomar Binay.

The 71-year-old mayor, who has vowed a ruthless campaign against crime and drug abuse, has not detailed how he will sustain the country's economic growth that is among the fastest in the world.