Francis Jeffers' 10-match guest stint with the Newcastle Jets is being compromised because of injury.

The former Everton and Arsenal striker signed with the A-League club for a short-term deal which runs for ten consecutive matches but if he misses any games due to injury, it counts in the overall term of the stay.

Jeffers strained his groin in Wednesday's 1-1 draw with Central Coast Mariners and may miss this weekend's trip to Townsville to take on the North Queensland Fury.

If that is the case, it will be one less game he can play for the Jets - a rule which has perplexed Newcastle coach Branko Culina.

"I'm quite puzzled that they've made it like this," Culina said.

"With the player having to play in 10 consecutive games, you could be really, really unlucky like we were and have to play a lot of games in a short period of time and the player gets injured and misses, for argument's sake, two-thirds of them.

"That's pretty stupid. It's no good for anyone.

"The idea of having a guest player is that he adds value to the team and to the competition. But if he gets injured and is unavailable, he's no good to anyone."

The rule is up for review by the A-League at the end of the season but that will be too late for Jeffers as his deal runs out in early January.