US President Barack Obama is expected to send about 34,000 additional troops to Afghanistan, a US defense official was quoted as saying by news agencies Wednesday.

The US Defense Department official with direct knowledge of the process told media on Tuesday that there has been no final word on the decision, but planners have been tasked with preparing to send 34,000 troops.

The president is expected to officially announce the plan to the public "early next week."

Obama said earlier on Tuesday that he would announce his administration's decision on a buildup of US forces in Afghanistan "shortly" at a joint news conference with visiting Indian Prime Minister Manmohan Singh.

The White House Tuesday also said that the president is expected to announce the Afghan decision "within days."

Obama ordered more than 20,000 additional troops to Afghanistan in March this year. Gen. Stanley McChrystal, the US commander in Afghanistan, has reportedly called for up to 40,000 more to wage the counterinsurgency campaign against the Taliban.

As the public is turning negative toward the Afghan war and his fellow Democrats are increasingly vocal in their opposition to a troop buildup in Afghanistan, the upcoming decision is regarded as one of the most critical moments to shape Obama's presidency.