Washington(CNN) The US is withdrawing from the United Nations Educational Scientific and Cultural Organization, the US State Department announced on Thursday, citing anti-Israel bias and mounting membership dues owed to the international body.

The "Department of State notified UNESCO Director-General Irina Bokova of the US decision to withdraw from the organization and to seek to establish a permanent observer mission to UNESCO," State Department spokesperson Heather Nauert said.

"This decision was not taken lightly, and reflects US concerns with mounting arrears at UNESCO, the need for fundamental reform in the organization, and continuing anti-Israel bias at UNESCO," she added.

Israeli Prime Minister Benjamin Netanyahu said Israel is also planning to withdraw from the body, according to a statement from the Prime Minister's office.

In the statement, Netanyahu hailed the US move as a "courageous and moral decision." He said UNESCO had "turned into a theatre of the absurd; instead of preserving history, it twists it."

The US stopped paying dues to the international body in late 2011 after the agency voted to accept a Palestinian bid for full membership and now owes approximately $550 million, a State Department spokesperson said.

"The purpose of UNESCO is a good one," US Ambassador to the United Nations Nikki Haley said in a statement. "Unfortunately, its extreme politicization has become a chronic embarrassment."

Haley called the decision to classify the Tomb of the Patriarchs as a UNESCO World Heritage Site "just the latest in a long line of foolish actions, which includes keeping Syrian dictator Bashar al Assad on a UNESCO human rights committee even after his murderous crackdown on peaceful protestors."

The Tomb of the Patriarchs, along with the Hebron's Old City, were designated as UNESCO World Heritage Sites in July, despite opposition from the United States and Israel. The site is regarded as sacred by Jews, Christians and Muslims. Israel has accused UNESCO of making a politically motivated move, part of what it says is an attempt to deny the Jewish character and heritage of certain key sites in the Holy Land.

United Nations Secretary General António Guterres expressed deep regret over the US decision to leave UNESCO, according to Deputy UN Spokesperson Farhan Haq.

The UN General Assembly President Miroslav Lajčák is also "concerned that the decision by the United States to withdraw could have adverse impacts upon the important work of UNESCO," according to a statement from his spokesperson.

UNESCO is a body of the United Nations that promotes international cooperation in education, science, culture and communication, though it is perhaps best known for its designation of "world heritage" sites -- locations with particular cultural significance.

It was founded in 1945 as allied countries "were looking for ways and means to reconstruct their systems of education once peace was restored" in the wake of World War II, according to the organization -- which currently has 195 members and eight associate members.

"Among other efforts, UNESCO is committed to building the capacity of various individuals and stakeholders to develop and amplify innovative responses against extremism; all while promoting the protection of freedom of expression, privacy and other fundamental freedoms," Bokova wrote in a CNN op-ed in September.

In a statement released via her official Twitter handle, Bokova called the withdrawal "a loss to UNESCO. This is a loss to the United Nations family. This is a loss for multilateralism."

She paid tribute to what she said had been a meaningful relationship between UNESCO and the US, saying: "since 2011, we have deepened the partnership between the United States and UNESCO, which has never been so meaningful. Together, we have worked to protect humanity's shared cultural heritage in the face of terrorist attacks and to prevent violent extremism through education and media literacy."

"At the time when the fight against violent extremism calls for renewed investment in education, in dialogue among cultures to prevent hatred, it is deeply regrettable that the United States should withdraw from the United Nations agency leading these issues," Bokova said in the statement.

"At the time when conflicts continue to tear apart societies across the world, it is deeply regrettable for the United States to withdraw from the United Nations agency promoting education for peace and protecting culture under attack," the statement said.