A far-left activist who advocates widespread nationalisation snatched first place in Peru’s presidential election on Sunday and is likely to face a staunchly conservative candidate in a highly polarising second round.

Pedro Castillo, a teacher from the provinces who rode to cast his vote on a bucking horse, was leading a highly fragmented field of 18 presidential candidates vying to govern a country wracked by one of the world’s worst coronavirus death tolls and widespread corruption.

With 49 per cent of ballots counted, Peru’s national electoral authority said Castillo lay in first place with 16 per cent of the vote, more than two percentage points clear of his nearest challenger, Hernando de Soto, a 79-year-old free-market economist.

A fast count by Ipsos predicted, however, that when all votes were counted, Castillo would face Keiko Fujimori, daughter of jailed former strongman president Alberto Fujimori, in a run-off election in June. A highly divisive figure, Keiko has been under investigation for corruption charges, which she denies.

Peru, the world’s second largest copper producer, has been gripped by chronic political instability in recent years and repeated corruption scandals which have fuelled disillusionment with the political class. More than 15 per cent of voters cast blank or spoilt ballots on Sunday in protest.

A 51-year-old from the province of Cajamarca in the northern Peruvian highlands, Castillo is best known for leading a teachers’ strike in 2017. During the election campaign his Free Peru party promised to nationalise the country’s mining, gas, oil, communications and transport networks and to pass legislation to control the media. It also wants to rewrite Peru’s Fujimori-era constitution.

“They have a socialist agenda, they talk a lot about the colonialism of the US and the OAS [Organisation of American States],” said Denisse Rodríguez-Olivari, a Peruvian social scientist. “It’s a very inward-looking vision which rejects any sort of foreign interference.”

Castillo has no Twitter account of his own and no website. He relies on grass roots support from outside the traditional — and despised — political elites of the capital. As polls opened on Sunday, Free Peru’s founder Vladimir Cerrón tweeted: “Today marks the beginning of the end for neoliberalism in Peru. Free Peru will dig its grave.”

The results gave the lie to most opinion polls. For much of the past month, Castillo had not figured in the top six candidates and his campaign only appeared to take off in the final days before the vote.

Peru now faces a highly polarising second round. Fujimori has the highest rejection rate in opinion polls of any of the leading candidates, which would boost Castillo’s chances if she is indeed confirmed as his rival.

The June run-off will give Peru its fifth president in as many years and whoever wins will face huge obstacles. The country has lurched from one political crisis to another and has had three presidents in the past six months alone. Most of Peru’s living former presidents are under investigation for corruption and congress is locked in a ceaseless battle for power with the executive.

Elections were also held on Sunday for congress and partial results suggested that none of the presidential candidates was close to commanding a majority in the single-chamber parliament. Free Peru was in the lead with 13.8 per cent, followed by Fujimori’s Popular Force grouping with 10.3 per cent and the leftwing Popular Action party with 9.4 per cent.

With 170.9 deaths per 100,000 inhabitants, Peru has the worst coronavirus death toll in Latin America, according to Johns Hopkins University data. On Saturday, the day before the election, Peru registered 384 deaths from the virus — its highest total in a 24-hour period since the pandemic began.

Gross domestic product shrank 11 per cent last year — the biggest contraction of any major economy in the region. The government’s tough lockdown measures crippled growth but failed to halt contagion.