The US says it is considering what part it will play on the UN’s human rights body, highlighting what it calls a “biased” stance on Israel.
UN ambassador Nikki Haley said the US was “looking carefully” at its role on the Human Rights Council.
She said it was “hard to accept” the fact that five resolutions had been passed against Israel, a US ally, but none had been considered on Venezuela.
Mrs Haley is expected to address the council later on Tuesday.
In an opinion article for the Washington Post last Friday, Mrs Haley said that the 47-member council needed to “end its practice of wrongly singling out Israel for criticism”.
While she highlighted work done by the group, she said not enough had been done to criticise Iran, a “country with an abysmal human rights record”, and Venezuela, which is in political turmoil and where dozens of protesters have been killed in recent months.
Criticism of the council was repeated on the Twitter feed of the US mission to the UN on Tuesday.
The council is able only to order investigations and record criticism of countries it judges to have violated human rights, but it acts as a crucial diplomatic tool.
In recent months, it has issued resolutions on human rights in North Korea, Haiti and Myanmar, among other countries.
Israeli Prime Minister Benjamin Netanyahu has previously called the body “an anti-Israel circus which attacks the only democracy in the Middle East and ignores the blatant violations of Iran, Syria and North Korea”.
And in 2013, Israel ended its working relationship with the group after it decided to investigate Jewish settlements in the West Bank.
Mrs Haley’s comments came after an opening address in Geneva by UN human rights chief Zeid Ra’ad al-Hussein calling on Israel to withdraw from territories it captured in the 1967 war.
He condemned what he called “a half-century of deep suffering under an occupation imposed by military force”.
Israel has occupied the West Bank, East Jerusalem and the Syrian Golan Heights since the war, 50 years ago this week. The UN also considers the Gaza Strip, which Israel pulled its troops and settlers out of in 2005, as part of occupied Palestinian territory.
Israel and the Palestinians blame each other for the failure to resolve the final status of the occupied territories after years of on-off peace talks.
In her Washington Post column, Mrs Haley called for a change in the procedure in electing new members to the council, saying that “the presence of multiple human rights-violating countries on the Human Rights Council has damaged both the reputation of the council and the cause of human rights”.
Among the current members is the key US ally, Saudi Arabia, which has been accused of rights violations, and whose accession to the group in 2013 was criticised.