Pakistan's Prime Minister Imran Khan will not attend US President Joe Biden's two-day Summit for Democracy being held in virtual format on December 9-10.

In a statement issued ahead of the meeting, the foreign ministry Wednesday said Imran would not attend, without offering an explanation.

While expressing appreciation for the invitation, the statement said: "We value our partnership with the US which we wish to expand both bilaterally as well as in terms of regional and international cooperation."

Pakistan is seen as moving increasingly closer to China but in a televised speech Thursday Khan said Islamabad has no interest in joining any bloc and he offered to help smooth relations between Beijing and Washington.

Yet Pakistan's relationship with the US has been fraught with suspicion on both sides.

Islamabad has baulked at Washington's often stated criticism that Pakistan has not been a reliable partner in the war on terror, accusing it of harbouring the Taliban even as they fought the US-led coalition.

Pakistan says it has lost 70,000 people to the war on terror since 2001 and said the country was ready to be a partner in peace but not in war.

However, other uninvited countries have shown their displeasure. Hungary, the only European Union member not invited, tried unsuccessfully to block EU Commission President Ursula von der Leyen from speaking on behalf of the bloc at the summit. During the 2020 campaign, Biden referred to Hungarian Prime Minister Viktor Orban as a "thug."

The White House declined to detail how it went about deciding who was invited and who was left off the list.

For example, Turkey, a fellow NATO member, and Egypt, a key US ally in the Middle East, were also left off. The Biden administration has raised human rights concerns about both nations. However, Poland, which has faced criticism for undermining the independence of its judiciary and media, was invited.

President Joe Biden Thursday opened the first White House Summit for Democracy by sounding an alarm about a global slide for democratic institutions and called for world leaders to "lock arms" and demonstrate democracies can deliver.

Biden called it a critical moment for fellow leaders to redouble efforts on bolstering democracies. In making the case for action, he noted his battle to win passage of voting rights legislation at home and alluded to the US' own challenges to its democratic institutions and traditions.

"This is an urgent matter," Biden said in remarks to open the two-day virtual summit. "The data we're seeing is largely pointing in the wrong direction."

The video gathering, something that Biden had called a priority for the first year of his presidency, comes as he has repeatedly made a case that the US and like-minded allies need to show the world that democracies are a far better vehicle for societies than autocracies.

The premise is a central tenet of Biden's foreign policy outlook – one that he vowed would be more outward-looking than his predecessor Donald Trump's "America First approach."

But the gathering also drew backlash from the US' chief adversaries and other nations that were not invited to participate.

Ahead of the summit, the ambassadors to the US from China and Russia wrote a joint essay describing the Biden administration as exhibiting a "Cold-War mentality" that will "stoke up ideological confrontation and a rift in the world."