Canada is holding off signing a landmark global treaty to regulate the arms trade – citing concern over how it affects firearm owners – even though the United States has now joined the global accord over the objections of that country's powerful gun lobby.

The Harper government considers Canadian firearms owners an important part of its political support base and in 2012 dismantled a federal long-gun registry, calling it an unnecessary burden.

U.S. Secretary of State John Kerry signed the Arms Trade Treaty Wednesday as world leaders gathered at the United Nations in New York. The Obama administration appointee insisted the accord won't erode the rights of American gun owners.

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The Arms Trade Treaty, which only covers cross-border trade and aims to keep weapons out of the hands of human rights abusers and criminals, still requires ratification by the U.S. Senate and has been attacked by the influential American gun rights group the National Rifle Association (NRA).

The NRA sharply criticized the Obama administration for its decision and vowed to fight ratification of the commitment. "This treaty threatens individual firearm ownership with an invasive registration scheme," the U.S. gun lobby said.

Mr. Kerry rejected the notion that binding the U.S. to the agreement would hinder Americans.

"This treaty will not diminish anyone's freedom, in fact the treaty recognizes the freedom of both individuals and states to obtain, possess and use arms for legitimate purposes," Mr. Kerry said after signing the treaty.

But in Canada, the Harper government remains concerned and is still studying the matter.

"If properly done, an Arms Trade Treaty can help limit the worldwide trade in illicit arms. Canada has always worked, and will always work, to keep arms out of the hands of criminals, terrorists, and those who abuse fundamental human rights," said Rick Roth, press secretary for Canadian Foreign Affairs Minister John Baird.

"That's why we were among the 154 countries that agreed to move this treaty forward."

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But, he said, Ottawa is still studying whether joining the accord would have consequences for Canadians.

"It is important that such a treaty not affect lawful and responsible firearms owners nor discourage the transfer of firearms for recreational uses such as sport shooting and hunting."

Mr. Roth said the Conservatives want to ensure they've thoroughly reviewed the accord.

"We will take the time to ensure the interests of Canadians are protected. We will do our homework, to make sure that any treaty we sign onto is good for Canada, and good for Canadians. That is what Canadians expect of their leaders," he said.

"We're consulting a broad range of organizations, industry, and individuals as well as the provinces and territories."

The Baird spokesman noted Canada has supported international efforts keep arms out of the hands of criminals, terrorists and human rights abusers, including helping surface to air missiles and conventional weapons from countries such as Sudan and Libya, and backing arms control programs in the Caribbean, Colombia, and Central America.

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The NRA in the United States warns the arms treaty will lead to a sort of firearms registry in the United States.

The accord, the U.S. lobby notes, "includes 'small arms and light weapons' within its scope, which covers firearms owned by law-abiding citizens. Further, the treaty urges record keeping of end users, directing importing countries to provide information to an exporting country regarding arms transfers, including 'end use or end user documentation' for a 'minimum of ten years,'" the NRA said in a statement.

"Each country is to take measures, pursuant to its national laws, to regulate brokering taking place under its jurisdiction for conventional arms. Data kept on the end users of imported firearms is a de facto registry of law-abiding firearms owners, which is a violation of federal law."

NDP foreign affairs critic Paul Dewar says the Harper government has no legitimate reason to balk at signing the treaty.

"The fact that the government continues to refuse to sign the treaty indicates a preference for conspiracy theories by pro-gun lobby over the simple truth. This is a treaty that will help save the lives of millions of civilians around the world and it has no impact on domestic owners of firearms," Mr. Dewar said.

With files from Reuters