Doctors late on Thursday struggled to treat a stream of wounded victims as bloodied patients lay on stretchers at city hospitals and anguished relatives clamoured for news of their loved ones.

The attacks came at a time when India was on alert after the recent hanging of a separatist unleashed protests in the Muslim-majority region of Kashmir.

Shinde said that while authorities had received intelligence of a possible threat of attack, "it was not specific".

Questioned about the Indian Mujahideen´s possible involvement, Shinde said it was too early to say.

"The investigation has just started ... we will find out everything," he said.

Commenting on the upcoming Test match in Hyderabad, Cricket Australia chief executive James Sutherland said he was taking advice from authorities.

"As far as I´m concerned we are playing the second Test in Hyderabad next week. That´s where we are at," said Sutherland, who is with the team in Chennai for the opening Test starting later Friday.

Newspaper headlines summed up the anger and frustration in India over the latest round of violence to strike the country.

"India´s enemies strike Hyderabad," said the Hindustan Times, while tabloid Mail Today said: "Serial Terror Returns to Hyderabad."

In May 2007, at least 11 people were killed in a blast at a mosque in Hyderabad and five more died when police fired at Muslim protesters.

Months later in August, at least 40 people were killed in Hyderabad when two blasts hit an auditorium and an outdoor restaurant.

Foreign Secretary Ranjan Mathai, the top civil servant in India´s external affairs ministry, did not rule out foreign involvement. "I am not sure there is any evidence it could be homegrown terrorism," he said in Washington Thursday.

New US Secretary of State John Kerry said in a tweet that he had expressed his sympathies for the "brave people" of Hyderabad when he met Mathai in Washington.

UN Secretary-General Ban Ki-Moon "strongly condemn(ed) the indiscriminate attacks" while Hugo Swire, a minister in Britain´s foreign office who is currently in India, said the attacks were "a shocking reminder of the terrorist threat this country faces".