India was warned by the US in October that the Taj Mahal Palace Hotel was a hot target for a potential terrorist strike, according to reports.
America's ABC News claims a US intelligence official revealed that Indian security agencies were told nearly two months ago that militants might come from the sea to attack hotels and businesses.
It adds that a second source confirmed that specific locations - including the Taj - were given in the warning.
India's Intelligence sources told the national NDTV news channel they had issued a series of warnings of a possible attack on Mumbai by sea in the months leading up to last week's devastating onslaught.
However, many Indians have expressed anger at apparent intelligence lapses, including what a senior coast guard official said was a warning militants would attack Mumbai from the sea days before it happened, and a slow reaction by security forces to the rampage.
Ratan Tata, the head of the Taj Group of hotels which owns the Taj Mahal hotel, earlier told CNN that they had received a warning that an attack might take place.
He said: "We did have some measures too, you know, where people couldn't park their cars in the portico where you had to go through a metal detector.
"But if I look at what we had, which all of us complained about, it could not have stopped what took place.
"They didn't come through that entrance. They came from somewhere in the back."
Indian officials have said they believe that Pakistan-based Islamic militant group Lashkar-e-Taiba is responsible for the attack.
They claim all the gunmen involved in the 60-hour assault were Pakistanis and that "elements" in Pakistan were to blame for the attacks.
However, Pakistan Prime Minister Yousuf Raza Gilani has urged India to provide evidence that Pakistanis were involved in the attacks - and promised to cooperated if proof was given.
"They have given us some of the organisations ... but that is not evidence. If they will give us evidence we are commmitted that we will extend full cooperation," Mr Gilani said in an interview with CNN.
-Sky News.