According to Reuters, Apple sued Nokia over the same nine implementation patents it has challenged the company over in the U.S. A spokesperson for Nokia said the company was investigating the claims.
The first shot in the legal battle between the two companies fired by Nokia last October, when it accused Apple's iPhone of violating patents related to GSM and wireless LAN technology. It is believed that Nokia's losses in the market prompted the company to sue over the alleged use of 10 patented wireless standards in the iPhone.
Apple then responded to Nokia with its own lawsuit, accusing the Finnish company of infringing on iPhone-related patents.
The battle of the two smartphone giants is expected to drag out for years, with both companies looking for a court hearing to be held in 2012. The U.S. International Trade Commission -- the group with which the complaints were filed -- has agreed to look into both Nokia's and Apple's complaints against the other.
Earlier this month, Nokia's CEO stepped down, and Stephen Elop, former head of Microsoft's Business Division, took over. The company also revealed that its chairman will depart in 2012.
Nokia remains the largest mobile phone company, in terms of market share, but it has lost significant ground to Apple since the iPhone launched. Apple has also commanded the lion's share of profits in the smartphone market.