WELLINGTON, Feb. 5 (Reuters) - New Zealand government ministers were heckled by protesters and their speeches drowned out by song on Monday as they arrived in the town of Waitangi for anniversary celebrations of the signing of New Zealand’s founding document, the Treaty of Waitangi.

Prime Minister Christopher Luxon and some coalition government ministers were welcomed by local Maori to the site of the signing in a traditional ceremony, but leaders of the two smaller government parties were interrupted by protesters displeased at moves to change indigenous policies.

During the welcome, or powhiri, Luxon's speech only went ahead after a Maori elder called for respect.

"I came here thinking we’d be challenged and there’d be a range of views around the table, around the conservation, which there was," Luxon told reporters. "I understand there are really big differences."

New Zealand's centre-right coalition is promising to undo policies of previous governments, particularly those promoting the official use of the Maori language and seeking to enhance Indigenous living standards and rights.

The government has also said it will introduce, but are not committed to passing, a bill that would reinterpret the Treaty of Waitangi.

Earlier on Monday, hundreds of protesters carrying white flags and holding plywood signs with the words Toitu Te Tiriti, or Honour the Treaty, arrived at the Waitangi venue.

Critics say the moves are the most significant step backward for Maori rights in decades, and some have taken legal action against the government to stop the policy changes.

Protests are planned for the main celebration day Feb. 6, marking the day in 1840 when the Treaty of Waitangi was first signed between the British Crown and more than 500 Maori chiefs.

Organiser are expecting upwards of 60,000 people to attend Waitangi Day events, which started on Saturday making it the biggest event since the 150-year celebrations in 1990.

Protest has long been part of Waitangi celebrations and in 1995 official events had to be cancelled due to anger over government policies. In 2016, a minister was struck in the face by a dildo thrown by a woman protesting a trade agreement.

Photo from Reuters