MANILA - The Philippines backs the United Nations (UN) Security Council's decision to impose stiffer economic sanctions against North Korea, Foreign Affairs spokesman Robespierre Bolivar said Sunday.

"The Philippines has been consistent in its support for the various UN Security Council resolutions," Bolivar told reporters in a statement.

The UN Security Council on Saturday unanimously imposed new sanctions on North Korea that could slash by a third the Asian state's $3 billion annual export revenue over Pyongyang's 2 intercontinental ballistic missile tests last July.

The US-drafted resolution bans North Korean exports of coal, iron, iron ore, lead, lead ore and seafood. It also prohibits countries from hiring more North Korean laborers, bans new joint ventures with Pyongyang and any new investment in current joint ventures.

Foreign Affairs Secretary Alan Peter Cayetano earlier said Manila is looking into Washington's call to downgrade diplomatic ties with North Korea.

"The less we talk, the more grave the situation can become," Cayetano told reporters last week.

Foreign ministers from the Association of Southeast Asian Nations (ASEAN) expressed "grave concern" over North Korea's continued nuclear and ballistic missile launches that "threaten peace, security and stability in the region."

The ministers however said North Korea will not be expelled from the ASEAN Regional Forum, a key security forum between the regional bloc's 10 member countries and 17 other dialogue partner states.

Pyongyang has been been with the ARF since 2000. It is the only forum where North Korea was a participant, and could be a venue for continuing discussions, Cayetano said.

US Secretary of State Rex Tillerson and Pyongyang's diplomatic contingent are set to meet with other foreign ministers here on Monday to discuss the denuclearization of the Korean Peninsula, overlapping claims in the South China Sea and the global threat of terrorism.