American children’s television network Nickelodeon says it has abandoned plans for a themed resort on an island known as the Philippines’ last ecological frontier following a backlash from environmentalists.

Nickelodeon said in January that it would build an “undersea attraction and resort” on Palawan island that would let fans “interact with the brand and the iconic characters they love”, including SpongeBob SquarePants and Dora the Explorer.

The announcement triggered fierce criticism from environmental campaigners who said it would destroy the area’s world-famous marine ecosystem, and an online petition calling for the project to be scrapped attracted more than 260,000 signatures.

Viacom International Media Networks, which owns Nickelodeon, said on Wednesday it had abandoned the project.

“[Viacom] and Nickelodeon will no longer be involved with this proposed development,” the company said in a statement. Viacom said the decision was “mutually agreed” with its Philippine partner, Coral World Park.

The statement did not say why Viacom had pulled out and its regional spokeswoman would not elaborate when contacted.

Conservation groups call Palawan “the last frontier” because of its pristine coastlines and forests, which are among the oldest and most diverse in south-east Asia. It is home to two Unesco world heritage sites – a subterranean river and the Tubbataha coral reefs.

Viacom’s initial statement in January promoted the project as its first resort in south-east Asia that “would give a significant business opportunity for our partners across multiple platforms”.

Viacom and Coral World Park also highlighted the project’s “ocean conservation focus” and plans for a giant marine sanctuary.

Environmental group Greenpeace on Wednesday hailed Viacom’s decision as a victory. “We commend Viacom for heeding the call of more than 200,000 online petitioners and the offline community campaign,” said Vince Cinches of Greenpeace South-east Asia. “They were able to dodge the bullet that has a huge reputational backlash for Nickelodeon, which has been claiming it is children-oriented.”

The Nickelodeon resort was meant to be part of Coral World Park’s 400-hectare (1,000-acre) development.

Coral World Park did not immediately respond to emails asking whether it would pursue the project following Viacom’s withdrawal.

The executive director of environmental group Save Philippine Seas, Anna Oposa, said the campaign against the development would not let up. “Our position and strategy will not change: we’ll continue to call on the local government of Coron and provincial government of Palawan to reject the project,” she said.