The captain involved in the Staten Island Ferry crash that killed 10 people has been suspended for refusing to cooperate with the federal investigation.
New York Mayor Michael Bloomberg says Michael Gansas has sent a letter to city officials saying he is refusing to talk.
The city transportation commissioner, Iris Weinshall, said she notified Gansas that he was suspended with immediate effect.
Mr Bloomberg said: "It's an outrage that somebody who can give us information refuses to talk. A person like that has no business working for the city, and we will take every legal action we can to get his testimony."
He added the city will institute a series of reforms including requiring an extra person to be in the pilot's cabin while the ferry is crossing New York Harbour, as well as when it is docking. The ferries will also be fitted with new radios and global positioning satellite technology, he said.
Federal officials had issued a subpoena for Gansas because he had cancelled a scheduled interview with the National Transportation Safety Board. Gansas's lawyer, Catherine Foti, confirmed she had received the subpoena but did not comment further.
Richard Smith, the assistant captain piloting the ferry when it ploughed into a maintenance pier last week, is still in a critical condition in hospital and unable to talk after attempting suicide.
The captain's whereabouts at the time of the crash are considered a vital element of the investigation. City regulations require the captain to be in the ferry's pilot house during docking, which could have provided backup if the pilot was stricken.
Gansas told police immediately after the accident that he was in the pilot house and that he tried to pull Smith off the controls after he lost consciousness. At least one deckhand has told investigators that Gansas was not in the pilot house.