Worcester Warriors players and staff are to have their contracts terminated, following part of the club being wound up in the High Court.
HMRC had been pursuing Worcester, who are suspended from all competitions, for unpaid tax of around £6m.
Diamond wrote on Twitter: "This is the darkest day for English rugby. We thought we could turn the tanker around but it’s ended up like the Titanic, sadly.
"The ship has sunk, the captains are nowhere to be seen. The RFU/PRL band played in the back ground. There are a privileged few who have jobs."
All 13 Premiership Club Owners Ranked By Their Net Worth
Gallagher Premiership owners are growing richer than ever before, but how much are they worth?
There's currently trouble at Worcester Warriors, which isn't awfully surprising when you compare their owners wealth to their Premiership rivals
Club states that it remains owned by 700 members, the shares held by John Lockyer, Bob Staddon, Paul Derbyshire and Ian Pugsley acting as trustees.
Leicester Tigers owner: N/A
Most recent annual return notes a large number of individual shareholders; club states that no person owns 50% or more of the club shares.
Saracens: N/A
No overall controlling party following the purchase of the club from Nigel Wray.
Northampton Saints owner: N/A
No overall controlling party.
Now, take a look through the gallery to reveal the estimated net worth of the Gallagher Premiership's owners and top shareholders.
9. Colin Goldring and Jason Whittingham: net worth - £3 million
8. Newcastle Falcons owner: Semore Kurdi net worth - £20 million
7. Harlequins owner: Duncan Saville net worth - £20 million
Ultimately owned by Union Mutual Pension Fund Ltd, registered in the tax haven of Bermuda. Reported to be owned by financiers Charles Jillings and Duncan Saville
6. Gloucester owner: Martin St Quinton net worth - £20.2 million
Ultimately owned by Martin St Quinton, who made his fortune from selling his company Azzurri Communications.
5. Sale Sharks owner: Simon Orange net worth - £25m
Owned by Simon Orange via a holding company, CorpAcq Ltd. The combined cash at bank value for all businesses where SIMON holds a current appointment equals £20.6m, a combined total current assets value of £99m with a total current liabilities of £119.9m and a total current net worth of £-25m.
3. Wasps owner: Derek Richardson net worth - £60 million
Owned by Derek Richardson via Moonstone Holdings, a company registered in Malta.
2. Bath owner: Bruce Craig net worth - £249 million
The accounts state that the ultimate controlling owner is the sole shareholder, Bruce Craig.
1. Bristol Bears owner: Stephen Lansdown net worth - £1.35 billion
Bristol City majority shareholder Steve Lansdown has lost £370m over the last 12 months, likely as a result of the Covid-19 pandemic, according to the Sunday Times.
Lansdown’s wealth is valued at £1.35bn, down from £1.72bn last year, and the Bristolian billionaire has fallen 22 places in the newspaper’s annual Rich List.
The 67-year-old Guernsey-based businessman is now ranked outside Britain’s 100 wealthiest people, dropping from No83 in 2019 to No105 in 2020.
#TOGETHER “This is the darkestday for English rugby. We thought we could turn the tanker around but it’s ended up like the Titanic, sadly. The ship has sunk, the captains are nowhere to be seen. The RFU/PRL band played in the back ground. There are a privileged few who have jobs.