salvador sanchez ceren
© Roberto Escobar/EPASalvadorean presidential favourite Salvador Sanchez Ceren after casting his vote accompanied in Sunday's election with his wife Margarita Villalta.
Salvador Sanchez Ceren was rebel leader in bloody civil war but with nearly half votes counted he is favourite to win March run off

A former leftwing guerrilla leader took a strong early lead in El Salvador's presidential election on Sunday but he could still face a run-off against a conservative rival who wants to deploy the army to fight powerful street gangs, early results showed.

Salvador Sanchez Ceren, a rebel commander who rose to the top of the now-ruling leftist Farabundo Marti National Liberation Front (FMLN) during El Salvador's civil war, had 49.2% support with votes in from about 45.4% of polling booths.

His rightwing opponent, former San Salvador mayor Norman Quijano, had 38.9%. If no one wins more than half of the vote, the two leading candidates will go to a run-off on March 9.

Two foreign election officials said they expected the vote to go to a run-off given a closer race in El Salvador's two most populated districts.

The FMLN took power at the last election in 2009 and Sanchez Ceren's campaign was helped by its popular welfare policies, including pensions and free school supplies.

"The Front is going to win because of the poor. They are giving us opportunities. My kids would not have been able to study without their help," said housewife Patricia Concepcion, 43, as voting wrapped up.

Even if he falls short of first-round victory, Sanchez Ceren appears to be in a strong position ahead of the run-off.

The third-place candidate Antonio Saca, who was president from 2004 until 2009, had about 11% support but it was not clear whether more of his supporters would back Sanchez Ceren or Quijano in a second round.

After leaving office, Saca broke away from Quijano's Nationalist Republican Alliance (Arena) party. The FMLN turned into a political party at the end of the civil war in 1992, and Sanchez Ceren has tried to appeal to moderate voters in this campaign as he looks to keep his party in power.

But the tight race reflects a deep divide that dates back to the 12-year war, which killed 75,000 people, and sluggish economic growth has contributed to the surge of violent street gangs.

Quijano is Arena's candidate and has campaigned on a promise of tough policies to crack down on the gangs.

"It is just terrible. You can't even leave your house because there is danger everywhere. It is time to
put and end to this," said Sandra Marin, 40, a shoe saleswoman.

Sanchez Ceren rejects the idea of deploying the army to fight the gangs and instead vows to forge a political pact to break through gridlock that has kept a divided Congress from carrying out reforms to tackle crime and weak economic growth.

"More than ever we need a new national accord, so that we do not have partisan policies but policies that are backed by all the people of El Salvador," he said after voting on Sunday.

Sanchez Ceren started out as a rural teacher and rose to become a top rebel leader during the civil war, when the FMLN fought a string of US-backed conservative governments.

He attended a mass early on Sunday at the chapel where Archbishop Oscar Romero was assassinated at the start of the civil war. Romero, who denounced oppression of the poor by country's military dictators, is a hero of the left.

The FMLN won power at the last election when it put up a popular journalist, Mauricio
Funes, as its candidate. He had no role in the civil war and has led the FMLN toward more moderate leftist policies.

Although many Salvadorans are terrified of the street gangs, a two-year-old truce between the Mara Salvatrucha (MS-13) gang and its rival, Barrio 18, has helped cut the number of murders in half from one of the highest homicide rates in the world to a 10-year low in 2013.

A victory by the right could disrupt that fragile truce if the military is used to battle the gangs. Quijano, a 67-year-old former dentist who became San Salvador's mayor, accused the FMLN of making deals with gangs to win votes in areas controlled by the criminal groups.