An awakening in the Muslim world about the atrocities committed in the west’s colonial past is feeding contemporary radicalisation of communities, said the Czech foreign minister on Wednesday.

In a dark speech that he described as brutal and difficult, Lubomír Zaorálek, the likely Social Democrat candidate for prime minister in the October elections, warned that the west had about 20 years to reach a settlement with the Muslim world.

Zaorálek was speaking at a Future of Europe Summit in Prague on the same day as his party met to decide who should lead it into the elections. It was expected to come with a complex deal whereby Bohuslav Sobotka, the unpopular prime minister, would not stand, leaving Zaorálek and interior minister Milan Chovanec in joint charge.

Facing a growing electoral challenge from populist forces, the Social Democrat-led coalition government’s response to the migrant issue is likely to feature strongly in the campaign, especially in the wake of an EU commission ruling this week that the Czechs, along with Poland and Hungary, are breaching an EU agreement to take a fixed quota of refugees. Zaorálek said he would not accept the EU decision.

In his speech, Zaorálek said nations including Britain, France, the Netherlands, Belgium, the US, the Russian empire and its Soviet successor had been responsible for the deaths of millions.

He said the west was facing a revolt from within about inequality caused by globalisation and from without by newly educated masses increasingly angry about their fate and their colonial past.

“We are facing an awakening now. We should be focussed on the non-western world, and the newly aroused political masses,” Zaorálek said. “Long-suppressed political memories are fuelling a large sudden and explosive awakening energised by Islamist extremists in the Middle East.” He said the same phenomenon could spread to Africa and Asia.

His remarks are likely to anger those who believe any reference to the west’s past can end up as part justification for extremist violence.

Zaorálek, admitting he was raising difficult issues, pointed to a delayed outrage fuelled by “education and new horizons” over slaughters “comparable in scale to the Nazi war crimes”.

“There is a big tendency to forget many things of our history,” Zaorálek said. “In India, from the second half of the 19th century, the British are suspected of killing up to 1 million civilians in reprisals stemming from the Indian uprising of 1857. The British East India Company’s use of Indian agriculture to grow opium and then essentially enforce it on China resulted in the premature deaths of millions.”

He continued: “In the Congo, 10 or 15 million were killed from the end of the 19th and beginning of the 20th century. In Vietnam, recent estimates suggest that between 1 to 3 million civilians were killed between 1952 and 1975.

“In the Muslim world, in the Russian Caucasus from 1864-67, 90% of the local population were forcibly rotated and between 300,000 and 1.5 million [people] either starved to death, or were killed. In Indonesia in the 19th century, the Dutch occupiers killed an estimated 300,000 civilians.”

He said that through the Algerian war of the 1950s, France had brutalised 1.5 million people, nearly half of the population. In neighbouring Libya, he said, an estimated half a million died between 1927 and 1935, partly due to Italian detention camps.

He added a million civilians had died in Afghanistan during the Soviet invasion. A further 160,00 civilians had been killed in the Iraq civil war at the hands of the US and its allies in the past 13 years.

Zaorálek said that “just as shocking as the scale of these atrocities is how quickly the west forgets about them”, adding it was necessary to recall these figures “when the west wants to speak about radicalisation and how is it possible we are facing so much hatred and violence”.

The only answer lay in persistent efforts to co-operate with Muslim countries, he said, adding the next 20 years represents “the last chance for the more traditional alignments with which we have grown comfortable”.

In the rest of the century, he said, the west will face a battle for survival largely due to the challenge of climate change.