Pete Bethune is lucky to be alive, following a knife attack in Brazil.

Kiwi environmentalist Pete Bethune is lucky to be alive.

Two men attacked Bethune on Wednesday morning (local time) in the port city of Santana, Brazil. One of the men lunged at him with a knife, while a second attacked from behind.

A fight ensued, lasting several minutes, and Bethune was knifed in his chest.

But the blade wedged between his ribs, preventing the attack from doing more damage than it did. A doctor told him he was extremely fortunate.

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"I'll never forget when I saw that knife come out of his pocket ... about a foot long and rusty," a shaken Bethune said.

"I honestly thought I was going to die today."

About 20 people watched on, but no one helped, he added.

Both attackers eventually fled the scene, one with Bethune's cellphone.

The city where Bethune was attacked is a 30 minute drive from Macapa, where Sir Peter Blake was killed in 2001.

Just before the incident, Bethune had visited the prison where the six men convicted of Sir Peter Blake's murder are currently being held.

He had begun the process of securing an interview with one of the prisoners, and was hoping to shed light on a "conspiracy theory floating around" that Blake's murder was linked to illegal gold-mining.

He was in the area looking at the illegal smuggling of pets, too, including monkeys and jaguar,and said there were "dodgy port towns at the mouth of the Amazon".

"The Amazon is for sale," he said.

Bethune said he was unlikely to pursue the interview with the prisoners now.

﻿Bethune is the captain of the MV Earthrace-2 and chief executive of Earthrace Conservation.

Earthrace director of operations Larisa Kellett said after the attack Bethunehad taken a motorbike ride back to his hotel where he patched himself up with dressings.

He then went to a hospital, where his knife wound was stitched up.

The attack was reported to police.

Bethune planned to return to Peru and then back to New Zealand next week.