The higher troop levels will come as Washington takes on bigger responsibilities in reconstruction and medical aid, including setting up of two mobile hospitals with facilities to perform major surgeries, military officials said.
Rear Admiral Michael LeFever, the Islamabad-based director of the US Disaster Assistance, told reporters via audio feed in the Pentagon that "there would probably in the vicinity of over 1,000 US armed forces on the ground supporting the efforts of Pakistan" probably by this week.
There are currently about 560 military personnel on the ground carrying out a multitude of tasks in the relief operations in Pakistan.
The US troops will be backed by Nato's reinforced engineering battalion of some 1,000 personnel and four helicopters pledged at the weekend by the alliance.
LeFever said that a mobile army surgical hospital set for launch on Tuesday in Muzaffarabad would "conduct surgical capabilities and continue to grow to be a fully-staffed hospital supporting that area within a few days".
"We expect to be conducting major surgeries along with ICU (intensive care unit) beds starting tomorrow (Tuesday) night," he said.
"We are flying in another hospital from Okinawa (US military base in Japan)" to be sited at Balakot, close to the epicentre of the devastating earthquake, LeFever said.
The US military has sent in 12 helicopters, with six more on the way.
Washington has pledged $50 million to Pakistan's recovery effort with more money expected to be promised at a global donors conference on the disaster in Geneva, officials said.
"They stood by us in the war on terror, we are here for the long haul to support them," LeFever quoted US Central Command Chief General John Abizaid, who toured the devastated areas on Sunday, as saying.