Top Mexican drug lord Joaquin "El Chapo" Guzman has escaped from a maximum security prison for a second time.

The Sinaloa cartel chief, who was serving a 20-year sentence, fled through a 1.5km tunnel connected to an elaborate hatch in the shower area of his cell, said officials.

The tunnel is also said to have had special ventilation tubing, lighting, and a motorcycle on tracks.

Security Commissioner Monte Alejandro Rubido told a news conference that 18 employees from various part of the facility have are being questioned.

A manhunt is under way and police have set up checkpoints and patrols in the vicinity of the Altiplano prison, west of Mexico City.

Guzman, who had a $5m US bounty on his head when he was seized by Mexican and US authorities in the seaside resort of Mazatlan in 2014, was last seen on Saturday evening in the shower area.

He subsequently disappeared from the prison's CCTV network before prison guards discovered his cell was empty.

His escape will be a blow to the administration of President Enrique Pena Nieto which had received praise for its work tackling the country's drugs cartels.

Since the government was elected in 2012 authorities have arrested or killed six drugs lords, including Guzman, who was caught by authorities for the first time in Guatemala in 1993.

After being extradited and sentenced to 20 years in prison on drug smuggling charges he escaped from Puente Grande prison in 2001 with the help of prison guards.

He was re-captured in February 2014 after being pursued by authorities for days across his home state of Sinaloa.

Former Mexican Attorney General Jesus Murillo Karam had dismissed concerns that Guzman could escape a second time. That risk "does not exist," he said.

Guzman was reportedly 56-years-old last year, though there are discrepancies in his birth date.

The US Drug Enforcement Agency believes he has surpassed the infamous drug lord of the 1980s, Pablo Escobar, in terms of both his notoriety and the scale of his operation.

Guzman's cartel is thought to control most of the major crossing points for drugs at the US border with Mexico.

Guzman had an estimated fortune of $1 billion, with Forbes having labelled him the "most powerful drug runner in history", and had made the magazine's list of the 'world's most powerful people' from 2009 until last year.