The all-rounder had been in outstanding form with the ball on his return from ankle surgery but complained of discomfort in his side while bowling against Durham last week.

Watkinson said: "It is early doors for me to make any comment. He'll need rescanning and reassessing. I'm just looking at the timescale of two or three weeks' recovery and a week to get match fit and that's where it takes us."

Lancashire sent Flintoff for a scan, after which he was told to rest for two to three weeks and missed the first Test at Lord's.

Flintoff's injury was expected to rule him out of the the second Test against the Kiwis but his is now thought likely to stretch to the third and final match in the series, which starts at Trent Bridge on June 5.

The 30-year-old would now need to prove his fitness in Lancashire's LV County Championship match against Yorkshire at Headingley, which begins on May 28, to push for inclusion but Watkinson admitted it was unlikely he would play in part.

He added: "I don't want to be making predictions but I don't think he will be back for the Roses game.

"Maybe Fred will be back against Nottinghamshire [on June 6], but it is early days. He is taking it easy this week."

England coach Peter Moores had confirmed this week that Flintoff, if fit, would have been included in England's squad for the first two Tests.

But the earliest he is now likely feature is the Twenty20 international against the Black Caps at Old Trafford on June 13.