A senior Israeli diplomat has given a positive view of Chuck Hagel's nomination as US defense secretary, though some commentators in the Jewish state expressed worries that the choice could open a new fissure in bedrock ties with Washington.

US President Barack Obama, a Democrat, named the former Republican senator for the Pentagon post on Monday, setting the stage for a confirmation battle with critics who question his commitment to Israel in its struggle with Iran and other regional adversaries.

But Israeli Deputy Foreign Minister Danny Ayalon, a former envoy to the United States, told the country's biggest-selling newspaper, Yedioth Ahronoth, in comments published on Tuesday: "I have met him (Hagel) many times, and he certainly regards Israel as a true and natural US ally."

Prime Minister Benjamin Netanyahu, a rightist favored to win national legislative polls on Jan 22, has yet to comment publicly on the nomination. He has had a testy relationship with Obama, though both insist their coordination on Middle East security is sound.

Israel, which receives about $3 billion a year in US defense grants, has at times angered the Obama administration by threatening preemptive war against the Iranians while world powers seek a diplomatic deal to resolve the crisis over Teheran's nuclear program.

Obama has also criticized the Netanyahu government's settlement of occupied West Bank land, which the Palestinians blame for the two-year impasse in their peacemaking with Israel.

The pro-Netanyahu newspaper Israel Hayom on Tuesday quoted an unnamed government official as saying the choice of Hagel was "very bad news", adding: "Clearly it won't be easy with him."

The official, reflecting the belief of several Israeli analysts that Obama would continue to set the tone for bilateral relations, suggested that having Hagel in the Pentagon would allow the US president "to play 'good cop'" with Netanyahu.

Many Republicans contend that Hagel, who left the Senate after 12 years in 2009, at times opposed Israel's interests. He voted several times against US sanctions on Iran and made disparaging remarks about the influence of what he called a "Jewish lobby" in Washington.

Hagel sought to beat back the bias allegations on Monday, telling the Lincoln Journal Star newspaper in his native state of Nebraska that his record showed "unequivocal, total support for Israel" and that he had "said many times that Iran is a state sponsor of terrorism.

"Furthering the peace process in the Middle East is in Israel's interest," Hagel added.

Despite the criticisms of Hagel, the White House believes it can garner enough support for him on both sides of the political aisle to win confirmation in the Democrat-led Senate.

A decorated Vietnam war veteran, Hagel has criticized the size of the US military, telling the Financial Times in 2011 that the Pentagon was "bloated" and needed "to be pared down."

Hagel has also been attacked by gay rights groups for remarks in 1998 questioning whether an "openly aggressively gay" nominee could be an effective US ambassador. He apologized for the comments last month, saying they were "insensitive".

Rumors of Hagel's appointment had circulated for weeks, drawing the ire of some pro-Israel figures in the US. The outcry reached Israel's media, with one Yedioth commentator predicting a Hagel Pentagon would be Netanyahu's "nightmare".

But Moshe Arens, a former Israeli defense minister, played down the effect of Hagel's nomination on Obama's strategies.

"In the US, policy is made by the president, not by the members of the Cabinet," he told Reuters, noting that Ronald Reagan, a former president considered warm to Israel, had a less-sympathetic defense secretary, Caspar Weinberger.

Reuters