(CNN) -- The United Nations should "urge" Iran to release political prisoners rounded up during the recent unrest following last month's disputed presidential elections, a group of Nobel Peace Prize winners have declared.
The laureates, including Desmond Tutu, said the detention of lawyer Shirin Ebadi is illegal.
The group of 10 Nobel laureates, including former South Korean President Kim Dae-jung and South African Bishop Desmond Tutu, made the request in a letter to the secretary-general of the United Nations on Monday.
They also cited a concern for fellow Nobel peace laureate Shirin Ebadi. The Iranian lawyer won the prize in 2003 for her push for democracy and women's and children's rights.
In their letter to U.N. Secretary-General Ban Ki-moon, the laureates said that Iranian news organizations published an anonymous letter that called for Ebadi's prosecution for violating Islamic and constitutional law.
"These allegations are unfounded and are widely seen as the regime's attempt to lay the groundwork for her illegal arrest and detention," the laureates wrote.
"We call upon you to warn Iranian authorities that Dr. Ebadi's arrest because of her human rights advocacy is a direct violation of the United Nations Declaration on Human Rights Defenders."
Ebadi has spoken out against the killing of Neda Agha Soltan, the Iranian woman whose death -- captured on amateur video during a Tehran protest -- has come to symbolize Iranian resistance to the government's official election results.
To assess the situation and any human rights violations, Ban should send a special envoy to Iran to investigate, the Nobel Prize winners wrote.
The laureates also asked that Ban urge the Iranian government to release individuals detained while peacefully participating in post-election demonstrations in Iran. Those protests erupted after the government announced that incumbent President Mahmoud Ahmadinejad won in a landslide over his nearest rival, Mir Hossein Moussavi, in the June 12 vote.
The widespread street protests and civil unrest led to the deaths of at least 20 demonstrators and the arrest of more than 1,000, according to Iranian state-run media. The numbers of casualties and arrests could not be independently verified by CNN because the Iranian government has banned international journalists.
The clampdown on the media followed initial video of the mass protests. Iran's supreme leader, Ayatollah Ali Khamenei, on Monday accused Western governments of having "clearly meddled in the internal affairs of Iran" and the American and European media of depicting "the people of Iran ... as rioters," according to the semi-official Fars News Agency.