The terrorists involved in the Mumbai blasts chose the sea route and came to the city in boats before spreading out in the metropolis to carry out their attacks, the Union home ministry said on Thursday.

"They (the terrorists) came by the sea route," Special Secretary (Internal Security) M L Kumawat said while replying to questions at a press conference in New Delhi [Images].

He said the terrorists, claiming themselves to be from a hitherto unknown Deccan Mujahideen [Images] outfit, took the coastal route and landed at Sasoon Dock.

From there they changed over to boats to reach the shore, he said.

Asked about the identity or nationality of the terrorists, Kumawat declined to reveal any detail saying it would hamper the investigations.

A Mumbai report quoting authoritative sources pointed to the involvement of at least some Pakistani nationals in the serial terror attacks.

"There are indications that the perpetrators of the crime, who arrived in Mumbai by boats, are Pakistani nationals," they told PTI on the basis of information gathered from captured terrorists.

Maharashtra Deputy Chief Minister R R Patil, who also holds the home portfolio, said: "we have total clues. But disclosing information would not help the case".

The Colaba police have impounded four boats allegedly used by the terrorists to reach the Mumbai coast.

Union Home Minister Shivraj Patil [Images] has been warning about the possibility of terrorists using coastal routes to sneak into the country. A special scheme to beef up coastal security is being implemented and over 70 coastal police stations have been sanctioned, including 12 in Maharashtra.