By Bill Heaney
Mr MacNeil was suspended from the party’s Westminster group last month after reportedly clashing with chief whip Brendan O’Hara, the SNP representative for Helensburgh and Argyll and Bute.
The party’s conduct committee met on Thursday to discuss his case after he refused to immediately rejoin the group at the end of his suspension.
Mr MacNeil, 53, a native of Barra, has represented the Na h-Eileanan an Iar (Western Isles) constituency since 2005.
He tweeted about his expulsion, using a kangaroo emoji to refer to the member conduct committee, which he suggests he believes the decision to expel him was made by a kangaroo court.
He said: “The Summer of Member Expulsion, has indeed come to pass. As I have been expelled as a rank & file SNP member by a ‘member conduct committee’.
“I didn’t leave the SNP – the SNP have left me. I wish they were as bothered about independence as they are about me!”
He was suspended from the Westminster group for a week in early July following reports of a row with Mr O’Hara, pictured left, in the House of Commons.
Later that month his membership of the party was suspended as he refused to immediately rejoin the SNP group.
He released a statement attacking the SNP leadership’s approach to independence, accusing it of a lack of urgency.
“I will only seek the SNP whip again if it is clear that the SNP are pursuing independence,” he wrote.
Thursday’s decision by the conduct committee means he cannot sit as an SNP MP any longer and appears to rule out any reconciliation with the party.
On Wednesday, SNP Westminster leader Stephen Flynn was asked about Mr MacNeil as he spoke to journalists on the by-election campaign trail in Rutherglen and Hamilton West.
He told the PA news agency the party’s MPs should not “pick and choose” when they hold the party whip.
However he said he would not give a “running commentary” on the conduct process and he “gets on well with Angus”.
Mr Flynn said he and his colleagues wanted a “positive outcome” but added this was not always possible in politics.
Angus McNeill was the SNP MP for Barra (pictured) in the Western Isles.