Parliament in Nigeria has voted to send a delegation to Saudi Arabia to check on the health of President Umaru Yar'Adua. He's been in hospital there since November, being treated for heart trouble. As Will Ross reports from Abuja, there is growing concern that the president's long absence is creating a power vacuum.

Up until now, only a handful of people close to President Yar'Adua have been kept abreast of his health condition. Even senior ministers have been kept out of the loop, and like the rest of the population have had to rely on rumours. But the calls for the president to step aside are growing, and Nigerians are starting to make it clear that they find the continued absence and subsequent power vacuum unacceptable. President Yar'Adua has now been out of the country for 50 days. There had been no sight or sound of him until earlier on Tuesday when he spoke to the BBC over the phone from his hospital bed. He sounded very weak, but said he hoped to get better soon and return to work.