A Nigerian opposition party has demanded visual proof that President Umaru Yar'Adua is fit to govern while out of the country receiving medical treatment.
The Action Congress party on Monday called for the government to provide dated, concrete evidence of the president's health.
Mr. Yar'Adua was flown to a Saudi hospital in late November suffering from what officials described as a heart condition. He has not made any public appearances or comments since.
An Action Congress party spokesman said it is necessary for Mr. Yar'Adua to reassure the country that rumors of his ill health are unfounded.
Opposition parties have called for the president to formally cede power to Vice President Goodluck Jonathan during his absence. The government has rejected those calls, saying President Yar'Adua can exercise his powers from abroad.
The vice president gave the country's traditional New Year's address this year, saying the president "maintained sustained interest and optimism" in state affairs.
The president's health has become a source of constant speculation in the local media, and set the country on edge ahead of the 2011 presidential election.
Some information for this report was provided by Reuters.