Phones will still be available Friday on a walk-in basis at Apple retail stores and from various wireless carriers and authorised Apple resellers.


Apple's website had intermittent outages last Friday because of heavy traffic as orders began online. The company said the 4 million orders set a new 24-hour record.


It did not immediately say what the old record was. Last year, Apple sold 9 million phones in the first three days they were on sale.


The new phones were announced last week and have larger screens, faster performance and a wireless chip for making credit card payments at retail stores by holding the phone near the payment terminal. The phones start at USD199 with a two-year service contact.


The phones will initially be available in US, Australia, Canada, France, Germany, Hong Kong, Japan, Puerto Rico, Singapore and the UK Availability will expand to more than 20 additional countries a week later.


A free update to Apple's iOS software for phones will be available to existing users on Wednesday. The new phones will come with that update, iOS 8.

Apple's stock rose 30 cents to USD 101.96 in midday trading on Tuesday.