Foul play has been dismissed as a cause of the sudden failure of a suspension bridge in Hawke's Bay which sent four tourists tumbling into a river.
Initial engineering reports indicated the partial collapse of the Hopuruahine suspension bridge on the Great Lake walk at Lake Waikaremoana was caused by an "unexpected" failure of a heavy duty iron chain.
One of the cables on the bridge failed on the afternoon of September 3 and four French trampers on the bridge at the time fell into the river.
They escaped with minor cuts and scratches.
"Initial reports indicate that the release of the tension cable was caused by an unexpected failure in a link of heavy duty iron chain," Department of Conservation general operations deputy director Mike Slater said.
"Further analysis of the chain is under way to understand why it failed but there is no evidence of any suspicious circumstances surrounding the failure.
"We hope that clears up unfounded claims about 'sabotage'.
"The engineers say there is nothing to suggest that."
Mr Slater said DoC was keeping the park board and Tuhoe fully updated on the ongoing engineering investigations into the incident.
"We expect to have a report to both organisations on the cable failure in the next week."
Te Urewera Board and DoC have had the remaining nine bridges on the Waikaremoana track checked.
"They have all passed engineering safety inspections and while the Hopuruahine Bridge is closed, the track itself remains open."
Mr Slater said the board and DoC were continuing to liaise with and support the four trampers affected by the cable failure.