(Reuters) - Afghanistan's Taliban militants on Monday decried a pact by rival election candidates to form a government of national unity as a "sham" orchestrated by the United States and they vowed to press on with their war.

Former finance minister Ashraf Ghani was named president-elect on Sunday after he signed a deal to share power with his opponent, former foreign minister Abdullah Abdullah, ending months of turmoil that has destabilized the country as most foreign troops prepare to leave.

Ghani's administration must now not only forge an effective government after so much acrimony, amid doubts about how long the pact will last, but must also deal with an emboldened Taliban insurgency.

Ghani was scheduled to hold his first news briefing as president-elect later on Monday.

The Taliban have been fighting to oust U.S.-led foreign forces and their spokesman, Zabihullah Mujahid, rejected the national unity government pact as an unacceptable ploy orchestrated by their enemy.

"Installing Ashraf Ghani and forming a bogus administration will never be acceptable to the Afghans," Mujahid said in a statement emailed to journalists.

"The Americans must understand that our soil and land belong to us and all decisions and agreements are made by Afghans, not by the U.S. foreign secretary or ambassador," he said.

"We reject this American process and vow to continue our jihad until we free our nation from occupation and until we pave the way for a pure Islamic government."

The Taliban ruled Afghanistan with their extreme interpretation of sharia law for five years before being toppled in 2001 with American support over their sheltering of al Qaeda's leaders after the Sept. 11 attacks in the United States.

Nearly 13 years later, the United States and Karzai have separately attempted to start peace talks with the resurgent Taliban, but they have seen little progress.

The United States strongly pushed for the power-sharing deal between Ghani and Abdullah in order to prevent the election dispute from descending into deadlock and even violence between supporters of the candidates, who draw their support from ethnic groups that fought a civil war in the 1990s.

U.S. Secretary of State John Kerry telephoned the rival candidates for weeks to coax them towards compromise and President Barack Obama also made appeals for a unity government deal.


A senior U.S. official said that Ghani and Abdullah, both pro-Western technocrats with similar political platforms, would be able to come together for the sake of the country despite the bitterness of the last two months.

Under the terms of the unity deal, Ghani will share power with a chief executive proposed by Abdullah. The two will share control over who leads key institutions such as the army and other executive decisions.

Ghani is expected to be sworn in as president on Sept. 29, according to a senior official. The new chief executive is expected to be inaugurated at the same time.

One of Ghani's first acts is likely to be to sign a long-delayed security agreement with the United States. He has previously declared support for the pact to allow a small force of foreign troops to remain in Afghanistan after 2014.

Many people in Kabul fear instability could be exploited by the Taliban, who have made significant gains in the south and east, taking advantage of gaps in U.S. air support this summer fighting season.

A U.S. official in Kabul said the deal to end the election dispute was far from ideal, but preferable to many alternatives that could pose a greater threat to stability.

Some Afghans worry that the competing interests of powers that seek influence in their country - including IranPakistan and India - may play into how the U.S.-brokered deal works out, a complaint often raised by outgoing President Karzai.

"Afghanistan' enemies and neighboring countries ... are waiting to see if this agreement brings a crisis," said Kabul member of parliament Qurban Ali Erfani, listing enemies as "the Taliban, some foreigners and our neighboring countries.”