Ever since Apple announced the iPhone software development kit (SDK) last October, developers and iPhone owners alike have been waiting anxiously for the company to release it. But despite speculation that it could arrive as early as Tuesday, a new report from BusinessWeek says the date has been pushed back to mid-March.

Arik Hesseldahl, a writer for BusinessWeek, is reportedly in contact with important figures close to the developments of the iPhone SDK. He claims his sources have confirmed that the development tool will slip from its intended release window this week.

Progress is 'fluid'

No justification is given for the delay, but the writer did claim that progress is currently "fluid". He also said that Apple could keep most of the product's development close to its chest so as to maintain a shroud of secrecy over the SDK.

"There are, apparently, a lot of moving parts to something this complex," Hesseldahl claims.

Apple did not comment on the story, but has said previously that it will not release the SDK until it knows that the kit is both robust and secure.