Five of the 11 Betfred Super League clubs have returned positive cases from the latest set of testing for Covid-19, the Rugby Football League has announced.

The RFL says that, of the 589 tests on players, match officials and other relevant staff since the start of the week, there were 10 positive results spread across five clubs.

The governing body do not reveal the identity of the players or their clubs but Castleford and Wigan both confirmed positive results for three of their players earlier in the week and on Thursday both Hull FC and Wakefield announced positive tests for one player each.

Castleford suggested they would not be able to play their match against Leeds on Thursday night after being left with just 14 players through injury and the knock-on effects of the coronavirus pandemic.

The Tigers, who stood down six others as a result of track and trace, offered to check on the fitness of three of their 11 injured players on the morning of the match in an effort to fulfil the fixture.

But Hull, who were without a fixture due to the withdrawal from the league of Toronto Wolfpack, agreed to replace them as Leeds' opponents, despite being without 13 players themselves.

The Black and Whites say they have had stand down three players through track and trace and also have nine players missing through injury.

Hull chairman Adam Pearson admits it is a risk playing the game at short notice but says the decision was made to repay a favour from Castleford.

"The reason we have done it is when we were forced to withdraw earlier in the season Castleford stepped up for us with no fuss and we wanted to do the same for them," Pearson told the Hull Daily Mail. "This decision is about the wider game, not Hull FC."

Hull have been able to name only a 19-man squad, including two potential debutants, but interim head coach Andy Last says there was a unanimous decision to play the game.

"After my initial shock, we spoke as a staff group and had a look at what was available to us in terms of the squad and felt comfortable that, if we had to do this, then we were prepared to do so, despite having so many players unavailable to us," Last said. "We all felt there was a bigger picture to consider.

"We spoke with the senior players within the group who understood the situation and realised the importance of keeping the game going and felt it was the right thing to do for their sport.

"It makes you very proud to see the character and commitment of the playing group when they're pulling together during times of adversity."

Wakefield say they would have sought the same solution as Castleford had it been open to them.

Trinity say they have just 17 players available for Friday's match against champions St Helens after being forced to stand down eight due to track and trace protocol.

"We've got 14 fit players and three guys out of a group of about five who are playing rock, papers, scissors to see who is the least injured," said Wakefield chief executive Michael Carter.

"If Cas hadn't have been in the position they were in yesterday, we'd have been the ones to ask Hull to play Saints on Friday and we'll pick up a fixture the week after.

"But if you go in chronological order, Cas have had their issues first and got that switch and we have nowhere to go. So we are playing tomorrow night. We will have 17 on the field and in the dugout – but that's all we've got."

Carter believes the safety protocols are being taken too far.

"We've got to stand down all and sundry and there's a couple of players within that group who cannot fathom out the logic of why they've been stood down," he said.

"And it's very difficult to explain to them because I don't think there is any logic to it.

"I would say 90 per cent of this is not through rugby-related contact but we're having to pay the price because basically whatever Public Health England say we've got to do."

Carter says he may seek special dispensation from the RFL to sign players if the club sustain any more injuries on Friday but insists clubs must attempt to finish the season.

"An hour ago, I was talking to Rushy (chief executive Mike Rush) at Saints about whether we can borrow three players off them to fill our bench," he added.

"That's the kind of co-operation we're getting from clubs. It's great that we're all pulling together.

"We're doing everything we can to make sure we fulfil fixtures.

"I absolutely understand that we've got to fulfil a broadcast deal because, if we don't, we're all packing it in any way."