Peruvian police told AFP all four tourists were British but the Foreign Office in London, also citing Peruvian police, said that only three of the four passengers were Britons.
Police told AFP that one of the British victims was a woman.
The Peruvians who died in the crash yesterday were the crew aboard a Cessna 185 belonging to AirNasca, one of the companies offering overflights of the Nazca lines, designs etched the desert some 2,500 years ago by a pre-Inca civilization that are best seen from the air.
"All of those who were aboard are dead. The plane crashed after taking off" from the local Maria Reiche airport, said a police official in Nazca, 460 km (285 miles) south of Lima.
The Cessna plummeted to the ground around 0345 IST and slammed into an agricultural field where the pilot was apparently trying to make an emergency landing, the official added.
A Foreign Office spokesman said Britain's ambassador to Peru and another member of the consular staff were making their way from Lima to the scene of the crash.
"The Peruvian authorities have notified us that three British nationals died in the plane crash in Nazca," the spokesman said.
Peruvian police "are attempting to identify the nationality and identity of the fourth passenger," he added.
The Maria Reiche airport may be small but it is especially busy: some 40 small airplanes use it as a base to taking tourists to see the Nazca lines.
Small plane emergency landings on highways are fairly common in the area.
In February four Peruvians and three Chileans died in a similar crash over the lines.
Five French tourists were killed in April 2008 when their small plane went down near Nazca, prompting the French government to issue a warning. Peru called it an overreaction.
Britain has also warned its nationals about Nazca flights in its Peru travel advice.