Dzhokhar Tsarnaev has told investigators that his brother Tamerlan orchestrated the Boston Marathon attacks because he “wanted to defend Islam from attack”, it emerged today.

In scrawled notes made from his hospital bed, Dzhokhar Tsarnaev, 19, told Guantanamo Bay interrogators that Tamerlan, 26, was motivated by the Iraq and Afghanistan wars and his belief that they represented an assault on his faith, according to reports.

Dzhokhar Tsarnaev told investigators that he and his brother were not linked to any Islamic terrorist groups. Instead, authorities believe Tamerlan Tsarnaev “self-radicalized” by watching online videos of extremist Muslim preachers.

According to CNN, Dzhokhar Tsarnaev said Tamerlan was the ringleader in the Boston attacks that shook the nation a week ago, but that the pair were working alone.

In preliminary interviews with Dzhokhar Tsarnaev, the terror suspect said his brother “wanted to defend Islam from attack”, a source told CNN.

Dzhokhar Tsarnaev has told investigators that his brother Tamerlan orchestrated the Boston Marathon attacks because he wanted to defend Islam from attack

The Washington Post reports that Tamerlan Tsarnaev believed he had to defend his faith because the US had waged war against Islam in the wars in Iraq and Afghanistan.

Two US officials said last night the evidence from the bedside interrogation suggests the terror suspects did not have any accomplices, despite previous fears they were part of a 12-man terror “sleeper cell”.

TamerlanTsarnaev died in a police shootout on Friday.

Dzhokhar Tsarnaev was formally charged with conspiring to use a weapon of mass destruction after being questioned by federal officials in his hospital room where he is recovering from multiple injuries.

He could face a death sentence, despite the fact Massachusetts has no death penalty, as he is being prosecuted under the federal system.

A probably cause hearing has been scheduled for May 30.

Investigators have been quizzing Dzhokhar Tsarnaev about whether there were more bombs, explosives or weapons beyond the ones already uncovered by police as well as who came up with the plot.

Interrogators are questioning Dzhokhar Tsarnaev in his room every few hours as doctors sit by his bedside, CNN reported.

The suspect is reportedly unable to speak because of a gunshot wound to the throat.

Dzhokhar Tsarnaev is believed to be communicating in writing to a special team of FBI counter-terrorism agents trained in interrogating “high-value” detainees that were sent to his bedside at Boston’s Beth Israel Deaconess Medical Center.