The Taliban says its political wing is ready to enter peace talks to end the war in Afghanistan.

In an emailed statement Thursday, the group said it has increased its efforts to bring about peace in the troubled nation. But it also reiterated its opposition to the current Afghan constitution, and it referred to the government led by President Hamid Karzai as a “stooge” administration.

The comments come as a senior U.S. diplomat, Marc Grossman, prepares to lead a delegation to the country next week in hopes of getting approval from President Karzai for peace negotiations with the Taliban.

Also Thursday, a Taliban spokesman said an online video that appears to show U.S. service members urinating on the bodies of dead Taliban fighters will not affect plans to begin talks. Zabihullah Mujahid said because the process is so preliminary, the video controversy will likely affect neither plans for talks or for a proposed prisoner exchange.

The Pentagon has said it is investigating the origin of the video but has not verified its authenticity.

Earlier this month, the Afghan Taliban said it has reached a preliminary agreement to open a political office in the Gulf state of Qatar, in a move that could help facilitate the talks.

Spokesman Mujahid said in a statement that the Taliban is asking for the release of prisoners held at the U.S.-run Guantanamo Bay detention facility in Cuba.

U.S. officials have recently been quoted as saying that Washington is open to negotiating a peace agreement with the Taliban, and that a possible deal could include the transfer of Taliban prisoners.

In December, Vice President Joe Biden said the Afghan Taliban are not America's enemies, and that the insurgent group did not represent a threat to the U.S. unless it continued to harbor al-Qaida terrorists.

U.S.-led forces ousted Afghanistan's Taliban government following the September 11, 2001 terrorist attacks on the United States. Those attacks were carried out by al-Qaida, which had training camps in Afghanistan.