Kevin Pietersen has been ruled out of the Test series against New Zealand after it was decided he needed further time to recover from his knee injury.

Pietersen was forced to miss the final Test in New Zealand last month and was diagnosed with bruising on his right knee. He has since been wearing a brace to aid his recovery - which he has yet to come out of - and will not be risked for the two-Test series, which starts on May 16, with his next target being the Champions Trophy in June although the ECB have not confirmed a new timescale.

Pietersen, who is currently in Dubai, tweeted: "Injuries are a sportsman's worst nightmare! This one is hurting me the most.."

When he flew home from New Zealand his recovery time was estimated at around eight weeks which always left it unlikely that he would be fit for the start of the international season.

An ECB statement said: "England and Surrey batsman Kevin Pietersen has been ruled out of the upcoming Investec Test series against New Zealand as he continues his recovery from significant bone bruising to his right knee. Pietersen will have a repeat scan next week to determine when he is able to resume training."

Pietersen first picked up the problem before England's warm-up match in Queenstown ahead of the Test series, possibly when he slipped during a fielding drill, and although he played the Tests in Dunedin and Wellington he was not fully fit.

Although there is still a month before the New Zealand series starts at Lord's on May 16, the ECB have taken an early decision on Pietersen's fitness which will avoid conjecture and allow the selectors to assess the form of his likely replacements in the County Championship.

Jonny Bairstow came in for him in Auckland, as the only spare batsman on tour, and struggled having played one first-class innings in seven months. If the selectors maintain consistency, Bairstow should be the first in line to play at Lord's although the next few weeks of Championship action will allow others to stake their claim.