(Corrects new term length to four years (not six) in paragraph 5 and possible duration of presidency in paragraph 6)

LOME (Reuters) -Lawmakers in Togo approved changes to its constitution on Friday linked to presidential term limits and how presidents are elected, which some opposition politicians and civil society groups have denounced as a constitutional coup.

Parliament passed amendments in a vote in March, but further consultations and a second parliamentary vote were scheduled, and legislative elections were pushed back due to fierce backlash.

Those opposed to the changes fear they could allow further extensions of President Faure Gnassingbe's 19-year rule and his family's grip on power. His father and predecessor Gnassingbe Eyadema seized power in the coastal West African country via a coup in 1967.

In the second vote, lawmakers unanimously approved the amended charter under which the president will no longer be elected by universal suffrage, but by members of parliament.

The amendments also introduce a parliamentary system of government and shortened presidential terms to four years from five with a two-term limit.

It does not take into account the time already spent in office, which could enable Gnassingbe to stay in power until 2033 if he is re-elected in 2025, a highly likely scenario as his party controls parliament.

The amendments amount to a "project to ... confiscate power by a regime that is systematically opposed to any form of democratic change", a group of 17 civil society organisations said in a joint statement this week. They called on West Africa's main political and economic bloc ECOWAS to take action in response.

Several other African countries, including Central African Republic, Rwanda, Congo Republic, Ivory Coast and Guinea, have pushed through constitutional and other legal changes in recent years allowing presidents to extend their terms in office.

The West and Central African region has also witnessed eight military coups in the past three years.

Violent police crackdowns on political demonstrations have been routine under Gnassingbe, as they were during his father's long rule.

Faure Gnassingbe was last reelected in a 2020 landslide disputed by the opposition.

The new constitution also creates a new role, president of the council of ministers, with extensive authority to manage government affairs.

(Writing by Alessandra PrenticeEditing by Bill Berkrot and Helen Popper)

By Alice Lawson