Washington's UN representative Samantha Power said Thursday Afghanistan is owed no apology for US actions in the country since the overthrow of the Taliban 12 years ago.

"We have nothing to apologize for. Our soldiers have sacrificed a great deal," Power told CNN, as Washington hammered out the details of a new security agreement between Afghanistan and the United States.

The issue of whether or not the United State would offer an apology for mistakes made during the Afghan conflict had emerged as a possible sticking point in the final stages of long drawn out negotiations with Kabul.

A draft text of the agreement released Wednesday by Kabul said US forces remaining in Afghanistan after combat troops are withdrawn next year would be subject to American justice rather than local courts.

Power said the accord shows the strength of bilateral relations, and lays a strong foundation for future cooperation.

"What we're seeking to do is to secure an agreement that enables us to continue to work together beyond the end of the combat role in Afghanistan," Power said.

"Proof of how we're getting along is how much they want us to stay and continue to assist in the train/equipment/assist role," she said.

She added that a letter sent on Wednesday from President Barack Obama to his Afghan counterpart Hamid Karzai, saying he was "pleased" with the agreement, and calling it a "strong agreement for both our countries" underscores those solid ties.

"I think what the letter does, is (it)tries to offer the reassurance that the United States in whatever role it stays in -- and we're negotiating that, of course, training, equipping, assisting on counterterrorism -- will respect the rights and the privacy of the Afghan people. That's something that mattered to Karzai," Power said.

Power added: "We, of course always respect the Afghan people and try to avoid civilian casualties and have done that from the time we've been there."