Wellington, May 21 (IANS): A team of experts on Tuesday re-entered a coal mine in New Zealand, where 29 miners were killed in an accident in 2010, the government said in a statement.

Experts from the Pike River Recovery Agency (PRRA) broke the concrete seal at the mine's opening, allowing the entry of the victims' families, who had been asking for this operation for the last eight years, reports Efe news.

"The first steps through the double airlock doors will be private for families to witness," the PRRA said on Twitter.

Experienced miners entered the mine to examine the place before the rescue team enters the site to find the bodies of the miners, who were killed in an explosion on November 19, 2010.

"They're taking the first wall down today and then there's a lot of work to get up to the next seal and then the actual re-entry into the drift will take place after that," Bernie Monk, father of one of the miners who died in accident and long-time spokesperson for Pike River families, told Radio New Zealand.

Prime Minister Jacinda Ardern said on Monday that the re-entry would be a "symbolic moment" as the operation that could take "a number of weeks and months".

The re-entry into the mine, which was initially scheduled for February, was postponed several times owing to safety concerns, follows a year of preparations by the PRRA, including cutting the 31.5 inch wall of concrete built 98 feet from the entrance and ventilating the passageway.

The Pike River tragedy claimed the lives of 29 miners, 23 of them New Zealanders, three Britons, two Australians and one South African, aged between 17 and 62.

The miners were reportedly killed by trauma, burns or asphyxiation after an explosion of methane gas which buried them 2.5 km deep in a tunnel that lacked alternate access.

Five days later they were declared presumed dead after a second explosion at the site in the town of Greymouth on the South Island, in the second-largest mining accident in New Zealand's history.