WASHINGTON -- Canada's former foreign affairs minister is expressing skepticism about Iran as nuclear talks with that country enter a sensitive phase.

John Baird described his concerns about a possible nuclear deal during a question-and-answer session at the annual gathering of the biggest pro-Israel U.S. lobby group on Monday.

Thousands of people were on hand to hear Baird's remarks -- delivered just before Israeli Prime Minister Benjamin Netanyahu spoke to the same audience.

"We're deeply concerned about the direction that the government in Tehran is taking," Baird told the American Israel Public Affairs Committee.

"I don't buy this PR job from the new president of Iran."

Baird's skepticism about nuclear talks with Iran isn't new. The context, however, put him at the epicentre of the debate during a most critical moment.

The Israeli prime minister has veered off from the election-campaign trail at home to deliver a pair of major speeches in Washington, fuelling tensions with the Obama administration.

Hanging in the balance is a possible deal with Iran which could see it promise to scale down its nuclear program in exchange for a weakening of economic sanctions.

Baird said he doesn't trust the Iranian government, because of its continuing human-rights abuses, its support for terrorism and its continued backing of the Assad regime in Syria.

He expressed concern about the consequences of a nuclear Iran for the entire region.

"The last thing we need is a new nuclear arms race in the Middle East," said Baird, who resigned his cabinet post last month.

"I used to view Iran's nuclear program almost exclusively through the lens of Israel. But over the past four years I can tell you that just about every single Arab country in the Middle East shares the exact same concern we all share."

Netanyahu began his own speech by singling out Baird and former Spanish leader Jose Maria Aznar, calling them great friends of Israel.

"You are two champions of Israel," he said. "And you are true champions of the truth."

Relations have been a little chillier lately with the American president.

Netanyahu insisted that he has great respect for Barack Obama and his office and said the Israeli-U.S. relationship had survived major disagreements in the past and would overcome this one too.

"As our region descends into medieval barbarism, Israel is the one that upholds these values common to us and to you," Netanyahu said.

At issue is whether a potential deal with Iran would stop its pursuit of a nuclear weapon, as the Obama administration hopes, or accelerate it, as Netanyahu fears.

The Israeli leader is expected to lay out the causes for his concern in a speech to Congress on Tuesday. However, he won't be going to the White House. The president has refused to meet him, arguing it would be inappropriate to offer a platform to one side in a foreign election campaign.

Both the Israeli leader and the U.S. agree on one thing: Iran must not get a nuclear weapon. Netanyahu cast it as an existential threat to his country.

The U.S. says that's precisely what a deal would help achieve.

"The United States of America will not allow Iran to obtain a nuclear weapon, period," said Samantha Power, the U.S. envoy to the UN, who also addressed the group.

She said U.S. support for Israel was unwavering, and she listed ways that support had been manifested -- such as US$20 billion in military financing for Israel provided by the Obama administration, far more than for any other country and more than at any previous time in the history of U.S.-Israel relations.

The Canadian government issued a statement late Monday, after being asked about Baird's views and his decision to air them at this time in Washington.

On the substance of Baird's remarks, the government concurred Iran has an "appalling" human-rights record and accused it of "gamesmanship" with international inspectors.

On his choice of venue, the government statement said: "Mr. Baird, MP for Ottawa West-Nepean, was in Washington on his own accord. While he was not representing the Government of Canada in an official capacity, we value his continued dedication in holding Iran to account."