APPLE has landed a crucial blow on its main rival Samsung in a two-year feud over alleged patent infringement by winning a key ruling in the top US trade court.

Samsung violated two of Apple's iPhone patents and must end the US import of some of its products, the International Trade Commission (ITC) ruled on Friday.

However, the ruling does not mean an instant ban on importing Samsung devices into the US.

A 60-day presidential review will take place, during which time the South Korean company will have the chance to implement a series of workarounds. A veto on the decision by President Barack Obama is not thought likely.

The ITC found Samsung had unfairly used Apple technology in some of its devices. It issued cease and desist orders banning further imports of some Samsung products, but dismissed four other claims made by Apple.

The verdict came as Apple asked an appeal court to force Samsung to stop using iPhone features that a jury had declared to be in violation of its patents. Apple is seeking to overturn a court order allowing Samsung to keep selling products that use the disputed patents.

Last year, a California jury found against the South Korean company and awarded Apple more than $1 billion (£645m) in compensation. The jury ruled 26 of Samsung's products violated six Apple patents.

The dispute comes at a difficult time for Apple, which is losing market share to smartphones using Google's Android operating system, many of which are made by Samsung. According to the International Data Corportation, Apple's share in the worldwide smartphone operating system market fell in the second quarter of 2013 compared to the same quarter last year.

In Washington on Friday, a federal appeals judge heard testimony in a separate patent case between the companies relating to a decision last year, in which Samsung was found to owe Apple $1bn for infringing patents. That penalty was later struck to $450m (£290m), and Apple appealed. A verdict has not yet been issued.