The United States condemned as "cowardly" an apparent suicide attack on a crowded park in Lahore that killed at least 65 people Sunday, vowing to work with Pakistan to defeat those sowing terror in the country.

Children were among the dead and more than 200 people wounded when the apparent suicide bomb ripped through the parking lot of the popular park where Christians were celebrating Easter.

"The United States condemns in the strongest terms today's appalling terrorist attack in Lahore, Pakistan," National Security Council spokesman Ned Price said in a White House statement.

"This cowardly act in what has long been a scenic and placid park has killed dozens of innocent civilians and left scores injured."

Pakistan has been battling a homegrown Islamist insurgency since 2004, with groups such as the Pakistani Taliban routinely carrying out attacks as part of their struggle to overthrow the government.

But Lahore, Pakistan's cultural capital that lies on the country's eastern border with India, has been relatively more peaceful in recent years.

"We will continue to work with our partners in Pakistan and across the region, as together we will be unyielding in our efforts to root out the scourge of terrorism," added Price.