WASHINGTON: The wife of a US aid worker abducted in Pakistan is pleading for his safe return on the one-year anniversary of his kidnapping, saying her husband is in poor health and is missed by grandchildren who ask for him every day.

Warren Weinstein, a 71-year-old aid worker from Rockville, Maryland, was kidnapped last August after gunmen tricked his guards and broke into his home in Lahore.

Al Qaeda released a video in May in which Weinstein said he would be killed unless President Barack Obama agreed to the group's demands. It was not clear when the video was recorded.

The White House has called for Weinstein's immediate release but has said it won't negotiate with Al Qaeda.

His wife, Elaine, observed the anniversary of his disappearance Monday with a statement urging his release. She said he suffers from a heart condition, severe asthma and high blood pressure and fears that his health ''will deteriorate if he is not allowed to see the doctors and specialists that have helped keep him alive in recent years.''

Our grandchildren are growing and changing so fast. They miss their grandfather and ask for him every day. It is so difficult to explain why he can't be with them,'' the statement says.

''It is impossible to describe the pain and sadness my daughters and I feel. We are simply heart sick. I always imagined growing old with Warren and enjoying our family together.''

Weinstein was the country director in Pakistan for J.E. Austin Associates, a US-based development contractor that advises different Pakistani business and government sectors.

The company has said Weinstein worked with a wide range of Pakistani government agencies, and that his work helped create hundreds of well-paying jobs and raise the standard of living in communities where the businesses are located.

He had told his staff he expected to wrap up his latest project and move out of Pakistan within days.

''Warren loves Pakistan and lived there for eight years so he could dedicate his time and energy to working with the people. I don't understand why he was taken,'' Elaine Weinstein said in her statement.

In the video released in May by Al Qaeda's media arm and posted on militant websites, Weinstein sits in front of a white background, near books and what appears to be a plate of food, and makes a direct appeal to the president.

''My life is in your hands, Mr. President,'' Weinstein says. ''If you accept the demands, I live; if you don't accept the demands, then I die.''

The video came several months after one release in December by Al Qaeda leader Ayman al-Zawahiri, who said Weinstein would be released if the US stopped airstrikes in Afghanistan, Pakistan, Somalia and Yemen. He also demanded the release of all Al Qaeda and Taliban suspects around the world.

The FBI has been investigating the kidnapping, but Jacqueline Maguire, a spokeswoman for the FBI's Washington field office, said the bureau cannot discuss ongoing investigations.