Ethiopia's ruling coalition started talks with opposition groups on Wednesday on amending provisions of an anti-terrorism law that critics say has criminalised dissent, State-affiliated media said.

Watchdog groups say the 2009 law's broad definitions have been used indiscriminately against anyone who opposes government policy. Among its provisions, it makes anyone publishing information deemed to encourage terrorism liable to a jail term of up to 20 years.

The discussions follow the release on Tuesday of opposition leader Andargachew Tsige, who was sentenced to death under the law in 2009 over his role in the opposition group Ginbot 7, which the government has labelled a terrorist organisation.

The Fana Broadcasting Corporation said 14 political parties, including the ruling Ethiopian People's Revolutionary Democratic Front, were taking part in talks having "agreed to amend" unspecified articles of the legislation.

Human Rights Watch has previously said the law "grants authorities the power to prosecute journalists who publish articles about protest movements, armed opposition groups, or any other individuals deemed as terrorist or anti-peace".

Ethiopia has released thousands of dissidents since January as part of reforms that the government has pledged to undertake in the wake of violent unrest that broke out three years ago.

The protests were sparked by an urban development plan for Addis Ababa that critics said would trigger land seizures in the surrounding Oromiya region, before broadening into rallies over political rights.

The unrest led to the resignation of Prime Minister Hailemariam Desalegn in February. He has since been replaced by former army officer Abiy Ahmed, who has pledged to push through reforms.

Andargachew's Ginbot 7 is among five groups the government had blacklisted under the anti-terrorism legislation, along with the secessionist groups Oromo Liberation Front and the Ogaden National Liberation Front, as well as the militant Islamist al Qaeda and Somalia's al Shabaab.

On Tuesday, the government pardoned Ginbot 7's leader Berhanu Nega, who had previously been sentenced to death.