President Asif Ali Zardari has traveled to Dubai for medical treatment of a heart condition, spurring rumors of his resignation.

The president's spokesman on Wednesday called the reports “untrue” and “imaginary.” He said Mr. Zardari's visit was a planned checkup.

Prime Minister Yousuf Raza Gilani's office said the president will remain under medical observation at a Dubai hospital in connection with symptoms related to a pre-existing heart condition.

News agencies quoted officials who said that the Pakistani president had suffered a minor heart attack.

Mr. Zardari was expected to return to Pakistan soon.

The president is facing pressure from a memo scandal that led to the resignation last month of Pakistan's ambassador to the United States.

In October, Pakistani-American businessman Mansoor Ijaz publicly accused former Ambassador Hussain Haqqani of writing an unsigned memo, requesting U.S. assistance to prevent a feared military coup in Pakistan. The letter was reportedly sent in May to Admiral Mike Mullen, the top U.S. military official at the time.

In return for U.S. help in preventing a military coup in Pakistan, the memo said a new national security team would conduct a full inquiry into allegations that Pakistan harbored terrorist leader Osama bin Laden. The new team also would hand over top al-Qaida members and ensure that Pakistan's military spy agency cuts ties to the Taliban, the Haqqani terrorist network and other groups.

Haqqani has denied any connection with the memo, and was replaced by former Information Minister Sherry Rehman.