HELSINKI - Nokia launched another patent case against Apple, in the latest step in an escalating legal battle between two leaders of the smartphone market.

Lawyers and analysts have said the legal battle between Apple and Nokia is likely to last for more than a year, with Nokia seeking payment of up to 1 billion euros ($1.45 billion).

Following are the key developments in the case:

NOKIA OCTOBER ATTACK

Nokia filed a suit in the United States in October, saying Apple iPhone had infringed 10 patents in technologies including wireless data transfer, a key factor in the success of iPhone. The suit accused Apple of trying to hitch a free ride on Nokia's technology investment.

APPLE COUNTERATTACK

Apple filed a countersuit on December 11 claiming that Nokia is infringing 13 Apple patents.

Other companies must compete with us by inventing their own technologies, not just by stealing ours, Bruce Sewell, Apple's General Counsel, said in a statement.

Nokia has until Feb 8 to reply to the countersuit.

NOKIA GOES TO ITC

On Dec 29 Nokia said it had filed a complaint with the U.S. International Trade Commission (ITC) alleging that Apple infringes seven Nokia patents in virtually all of its mobile phones, portable music players, and computers sold.

The inclusion of the U.S. firm's iconic iPod and iMac products in the complaint marked an escalation from the previous patent claims.

At the same time Nokia also filed a case at a Delaware court seeking damages for infringement of these patents.

($1=.6920 Euro) (Reporting by Tarmo Virki; Editing by Hans Peters)

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