HELSINKI (Reuters) - Nokia said a defective component in microphones, coupled with high demand, have hampered the availability of its flagship business phone, the E90 Communicator.

Background noise during phone calls, which raised customer complaints, was caused by a defective component in the microphone, spokeswoman Theresa Parenteau for Nokia Enterprise Solutions unit told Reuters on Tuesday.

"Although the issue is now rectified it has resulted in more limited availability than originally anticipated in some markets," she said.

When Nokia unveiled the phone in February 2007 it said it would start selling it in the second quarter in selected markets, with volume shipments coming in the July-September quarter.

Customers have also reported scratches on the phone screen caused by some keyboard keys touching the screen. Nokia said it has now added a strengthening layer on the screens and modified the keyboard, so the keys will not touch the screen.

The HSDPA and WLAN-enabled E90 Communicator, which features a full keyboard, retails for around 750-800 euros ($1,025-$1,093) before taxes and subsidies.