WASHINGTON -- Sen. John Kerry says Secretary of State Hillary Rodham Clinton has agreed to testify before the Senate Foreign Relations Committee about an independent report on the deadly Sept. 11 attack on the U.S. diplomatic mission in Libya.

In a letter Friday to the panel's members, Kerry indicated that the report from the accountability review board headed by retired diplomat Thomas Pickering is imminent. The Massachusetts Democrat and committee chairman says he's asked that Pickering and retired Adm. Mike Mullen appear before the committee before Clinton. Mullen, the former chairman of the Joint Chiefs of Staff, is a member of the review board.

The attack on the consulate in Benghazi killed U.S. Ambassador Chris Stevens and three other Americans.

Clinton has also agreed to testify before the House Foreign Affairs Committee.

Earlier on HuffPost:

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  • A burnt out vehicle sits smoldering in flames after it was set on fire inside the US consulate compound in Benghazi, late on September 11, 2012. (STR/AFP/GettyImages)

  • A broken window after an attack on the U.S. Consulate by protesters in Benghazi, Libya, Wednesday, Sept. 12, 2012. (AP Photo/Ibrahim Alaguri)

  • The U.S. Consulate after an attack by protesters in Benghazi, Libya, Wednesday, Sept. 12, 2012. (AP Photo/Ibrahim Alaguri)

  • A burnt car is seen after an attack on the U.S. Consulate by protesters in Benghazi, Libya, Wednesday, Sept. 12, 2012. (AP Photo/Ibrahim Alaguri)

  • Soot and debris spills out of the U.S. Consulate after an attack by protesters in Benghazi, Libya, Wednesday, Sept. 12, 2012. (AP Photo/Ibrahim Alaguri)

  • A man looks at documents at the U.S. consulate in Benghazi, Libya, after an attack that killed four Americans, including Ambassador Chris Stevens, Wednesday, Sept. 12, 2012. The graffiti reads, "no God but God," " God is great," and "Muhammad is the Prophet." (AP Photo/Ibrahim Alaguri)

  • A man walks on the grounds of the U.S. consulate in Benghazi, Libya, after an attack that killed four Americans, including Ambassador Chris Stevens, Wednesday, Sept. 12, 2012. (AP Photo/Ibrahim Alaguri)

  • Glass, debris and overturned furniture are strewn inside a room in the gutted U.S. consulate in Benghazi, Libya, after an attack that killed four Americans, including Ambassador Chris Stevens, Wednesday, Sept. 12, 2012. (AP Photo/Ibrahim Alaguri)

  • A man walks through a room in the gutted U.S. consulate in Benghazi, Libya, after an attack that killed four Americans, including Ambassador Chris Stevens, Wednesday, Sept. 12, 2012. (AP Photo/Ibrahim Alaguri)

  • Libyans walk on the grounds of the U.S. consulate in Benghazi, Libya, after an attack that killed four Americans, including Ambassador Chris Stevens, Wednesday, Sept. 12, 2012. (AP Photo/Ibrahim Alaguri)

  • Libyans walk on the grounds of the gutted U.S. consulate in Benghazi, Libya, after an attack that killed four Americans, including Ambassador Chris Stevens, Wednesday, Sept. 12, 2012. (AP Photo/Ibrahim Alaguri)

  • A vehicle and the surrounding area are engulfed in flames after it was set on fire inside the US consulate compound in Benghazi, late on September 11, 2012. (STR/AFP/GettyImages)

  • An armed man waves his rifle as buildings and cars are engulfed in flames after being set on fire inside the US consulate compound in Benghazi, late on September 11, 2012. (STR/AFP/GettyImages)

  • A vehicle burns after it was set on fire inside the US consulate compound in Benghazi late on September 11, 2012. (STR/AFP/GettyImages)

  • A vehicle sits smoldering in flames after being set on fire inside the US consulate compound in Benghazi late on September 11, 2012. (STR/AFP/GettyImages)

  • A vehicle and surrounding buildings smolder after they were set on fire inside the US consulate compound in Benghazi, late on September 11, 2012. (STR/AFP/GettyImages)

  • LIBYA CONSULATE

    Map locates Benghazi, Libya, where the U.S. ambassador to Libya and three other Americans were killed in an attack