UPDATE: Boston Marathon bombing suspect Dzhokhar Tsarnaev is awake and responding sporadically in writing to questions, according to unconfirmed reports on news.com.au.

The website, along with several news outlets, is reporting that Tsarnaev, 19, was responding sporadically in writing to questions from police investigators.

The report has not been veriifed by authorities.

Investigators were reportedly asking about other cell members and other unexploded bombs, law enforcement sources told ABC News.

The report was picked up by CNN's Piers Morgan, but veteran Al-Jazeera correspondent Alan Fisher cautioned that Tsarnaev was likely too ill to be reponsive.

Tsarnaev is being treated in Beth Israel hospital in Boston where he is listed as being in a “critical but stable condition” from wounds sustained in a shootout, police say.

Investigators believe his neck wound may be from a failed suicide attempt and not from the shoot-out that killed his brother, CBS News and The New York Times report.

Watertown

More: news.com.au