MANILA (Reuters) - A senator in the Philippines urged lawmakers on Tuesday to investigate China’s access to its power grid, warning of a security threat and possible sabotage due to its stake in the nation’s only transmission firm.

Risa Hontiveros filed a resolution warning of Chinese-engineered power and internet outages and interference in elections if safeguards remained absent, citing confirmation last week from a Philippine power executive that a “hostile third party” had the ability to cause blackouts.

Beijing and U.S. ally Manila have a long history of mistrust, despite Philippine President Rodrigo Duterte’s pursuit of warmer ties with China, largely concerning disputes in the South China Sea. Opinion polls consistently show Filipinos consider China an untrustworthy neighbor.

Ties were at their worst under the previous administration, when the Philippines infuriated China by seeking international arbitration over the conduct of its coastguard and its transformation of submerged reefs into de facto military installations.

Hontiveros said a country capable of aggression should not have the means to destabilize a neighbor “with the flick of a switch”.

“Imagine a foreign country, which is an unrepentant trespasser and aggressor in our seas and territories, controlling our national electricity grid,” Hontiveros said in a statement.

“It could sabotage our elections, shut down our access to television, the internet and other communication technologies, cause the collapse of our economy and undermine our national security,” she said.

China’s embassy in Manila did not respond immediately to a request for comment. There are no publicly known instances in the Philippines, or government accusations, of Chinese interference in its utilities.

Concern about China’s involvement in the power grid was first raised on Thursday during the energy department’s 2020 budget hearing in the Senate.

It also comes amid warnings by minority lawmakers that China Telecom's joint venture with Dennis Uy, a tycoon close to Duterte, could be a "Trojan horse reut.rs/2NXdg9g" for espionage. The consortium recently won approval to install communications equipment on Philippine army bases.

China’s State Grid Corporation owns a 40% share in a consortium called the National Grid Corporation of the Philippines, which in 2008 won a 25-year-franchise.