The rate at which the Lapindo mudflow is spewing in East Java might have slowed, but there is still no telling exactly when it will cease, the Sidoarjo Mudflow Mitigation Agency said on Sunday.

"The mud is now flowing at around 10,000 to 15,000 cubic meters per day," said Sofyan Hadi Djojopranoto, the deputy of operations at the agency known as BPLS. "However the BPLS cannot predict when it will stop."

Five years ago when the disaster began, the mud was gushing at a rate of at least 150,000 cubic meters per day, Sofyan said. Thousands of residents living on the edge of the disaster zone have since been displaced.

Scientists have long blamed a 2006 gas-drilling venture by Lapindo Brantas, part of the Bakrie Group, for triggering the disaster, claiming the company was negligent in its feasibility studies before drilling.

Lapindo, however, has maintained that it followed all necessary technical procedures before and during the drilling project and has insisted the mudflow was caused by a 6.3-magnitude earthquake that occurred in Yogyakarta days before.

Sofyan said more studies were needed, including on seismic activity in the area, before deciding what to do next. "We can only take action once we are certain that the mudflow is manageable and will not pose a future threat [to human health]."

Separately, in a discussion to commemorate Earth Day in Bandung, Akhmad Zaenuddin, who led a team from the Volcanology and Geological Disaster Mitigation Agency (PVMBG) researching and monitoring the disaster, said the flow would continue to decline after reaching its peak in 2008-09.

According to Akhmad, hardening mud had helped to close in the crater around the eruption site.

At the same event, Hermanto Dardak, the deputy public works minister, said the government would continue to strengthen the embankments around the mud lake until the eruption stopped.