That's a dramatic decline from the height of the rise of IS in 2014, when the extremist group seized about a third of both Syria and Iraq, before its downfall began.
The remarks by Defence Minister Sergei Shoigu came as Russia-backed Syrian troops are pushing deeper into the eastern Syrian town of Mehkan, one of the few still held by IS.
Speaking at a conference in the Philippines, Shoigu said yesterday that "terrorists", a term the Syrian government and its allies use for all armed opposition, including militant groups such as IS and al-Qaida's Syria affiliate controlled more than 70 per cent of the country before Russia launched its air operation at the end of 2015 to support President Bashar Assad's offencive against IS militants and opposition forces.
Later that year, IS started suffering setbacks that culminated with the fall last week of the northern city of Raqqa, the extremists' de facto capital. IS has also lost wide areas it once controlled in Iraq, including the northern city of Mosul, the largest city the group had ever captured. US- backed Iraqi government forces retook Mosul in July.
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Russia has played a main role in helping government forces capture wide areas from IS in northern and central Syria by giving them air cover. In September, Syrian troops and their allies reached the eastern city of Deir el-Zour, where the extremists had long besieged the government- controlled part of the city.
Now, with the IS "caliphate" rapidly crumbling, a race is on between the US-backed Kurdish forces and the Syrian government troops in the oil-rich Deir el-Zour province.
Syria's state TV said warplanes of the US-led coalition have bombed a government-controlled neighbourhood in the city of Deir el-Zour, the provincial capital, killing 14 civilians.
US military spokesman Col Ryan Dillon denied the report, tweeting that the coalition has not bombed the city, of which IS currently controls a small part, since September.
Last year, the US-led coalition bombed Syrian army positions near the city of Deir el-Zour, killing at least 62 Syrian soldiers and leaving more than a 100 wounded.
More than 400,000 people have been killed in Syria and half the country's prewar population displaced since the conflict erupted in March 2011.