President Asif Ali Zardari of Pakistan is being treated for a heart problem at a hospital in Dubai.
The government has rejected media speculation that Mr Zardari is to resign.
It says he is under medical observation for a pre-existing condition and will return after advice from his doctors.
Mr Zardari came to power after his Pakistan People's Party won elections in 2008.
The party was by his wife, former prime minister Benazir Bhutto, until she was assassinated in 2007.
The BBC reports Mr Zardari is understood to have undergone angioplasty in Dubai in 2005. The prime minister's office has referred to a "pre-existing heart condition".
