* UN climate panel report "in no way" tarnished * Review process makes bias impossibleLONDON, Nov 26 (Reuters) - The head of the U.N.'s panel of climate experts rejected accusations of bias on Thursday, saying a "Climategate" row in no way undermined evidence that humans are to blame for global warming. Climate change sceptics have seized on a series of e-mails written by specialists in the field, accusing them of colluding to suppress data which might have undermined their arguments. The e-mails, some written as long as 13 years ago, were stolen from a British university by unknown hackers and...