Indigenous campaigners who wanted Australia to create an advisory body representing its most disadvantaged ethnic minority have said its rejection in a constitutional referendum was a “shameful act”.

Many proponents of the Indigenous Voice to Parliament maintained a week of silence and flew Aboriginal flags at half mast across Australia after the October 14 vote deciding against enshrining such a representative committee in the constitution.

In an open letter to federal politicians dated on Sunday, campaigners said the result was “so appalling and mean-spirited as to be utterly unbelievable.”

The unsigned letter, which said it was written by Indigenous leaders, community members and organisations, said: “The truth is that the majority of Australians have committed a shameful act whether knowingly or not and there is nothing positive to be interpreted from it.”

Indigenous leader Sean Gordon said he was one of the many people who had drafted the letter.

“It was a statement that could allow Indigenous people across the country and non-Indigenous people across the country to commit to it and so signing it by individuals or organizations really wasn’t the approach that we took,” he told Australian Broadcasting Corporation.

Deputy Prime Minister Richard Marles, who heads the government while Prime Minister Anthony Albanese is in the United States, said he accepted the public’s verdict on the Voice.

He said: “The Australian people always get the answer right and the government absolutely accepts the result of the referendum, so we will not be moving forward with constitutional recognition.”

The letter writers blamed the result partly on the main opposition parties endorsing a No vote, accusing the conversative Liberal Party and Nationals party of choosing to impose “wanton political damage” on the centre-left Labor Party government instead of supporting disadvantaged Indigenous people.

No referendum has passed in Australia without the bipartisan support of the major parties.

Senior Liberal senator Michaelia Cash said voters had rejected Mr Albanese’s Voice model.

“Australians on referendum day, they did not vote no to uniting Indigenous people, they did not vote no to better outcomes for our most disadvantaged. What Australians voted no to was Mr Albanese,” she said.

The Indigenous writers said social media and mainstream media had “unleashed a tsunami of racism against our people” during the referendum campaign.

The referendum was defeated with 61% of Australians voting no.