GREYMOUTH, New Zealand — Another underground blast ripped through a New Zealand coal mine today almost a week to the minute after an earlier explosion caused the country’s worst mining disaster in decades, with 29 killed.

No one was injured in the latest explosion at the Pike River Coal mine, which is filled with explosive methane gas leaking from the coal seam.

The gas, plus a suspected fire smoldering deep underground that is a likely ignition source, has kept anyone from entering the mine since the first blast on Nov. 19 caught the 29 men inside. Hopes that they had survived were dashed by a second huge explosion on Wednesday.

Pike River Coal Chairman John Dow said the third explosion happened at 3:39 p.m. on Friday. The first explosion was recorded at 3:44 p.m. a week ago.

Dow said the third blast was smaller than the earlier two, and that no one was near the mine entrance when it happened.

It would not affect planning for an operation to enter the mine to recover the men’s bodies. Officials have said it could take weeks or months to complete the recovery operation.