About 12,000 people have rallied in the capital of Armenia to protest a constitutional change being proposed by the president.

Protesters and leaders of Armenia's three major opposition parties, which organized Friday's rally together despite their ideological differences, also called for the resignation of the government, blaming it for a dismal economic growth.

An ad-hoc commission was set up in Armenia early this year to consider potential changes to the constitution.

President Serge Sarkisian, who is now the head of state, has proposed a change that would make the prime minister the government's top official.

The opposition claims he has done that so he could run for that job when his second and final term as president ends in 2018 and thereby potentially remain Armenia's leader.