Apple has turned down an invite to testify before a European Parliament special committee on tax evasion, saying it doesn't want to prejudice its appeal of an EU ruling that the iPhone maker must pay almost $15 billion in back taxes to Ireland.

Sven Giegold, a member of the European Parliament from Germany, released Apple's letter to the special committee on Twitter on Friday.

In 2016, the EU ordered the Apple to pay almost $15 billion in back taxes to Ireland. The EU believes Ireland hasn't been collecting enough taxes and instead has been giving companies like Apple too big of a break on its already low 12.5 percent tax rate. Both Apple and Ireland are appealing the EU fine. 

In the letter to the special committee, Apple offers to speak with Parliament members privately.

Apple didn't immediately respond to a request for comment.