DUBAI, Jan 6 (Reuters) -

An earthquake hit an area in western Iran near the Iraqi border on Sunday, injuring about 31 people, most of them lightly, the state news agency IRNA reported.

The U.S. Geological Survey (USGS) initially put the magnitude of the quake at 5.9 but revised this later to 5.5.

Iran's emergency services spokesman Mojtaba Khaledi told IRNA that 29 of the injured had been released after treatment following the earthquake in Gilan Gharb in Kermanshah province.

An official in the province told IRNA on Monday that 44 aftershocks were registered after the initial quake, with 4-5 tremors having around 4.5 magnitude.

In November, a 6.3 magnitude earthquake shook western Iran, injuring more than 700 people, with most suffering minor wounds.

Iran sits astride major fault lines and is prone to frequent tremors. In 2003, a 6.6 magnitude quake in southeastern Kerman province killed 31,000 people and flattened the historic city of Bam.