Allies of Nigeria's ailing¹ president forged his signature on the country's supplementary² budget last month, opposition³ politicians have alleged⁴.

尼日利亚反对党政客宣称，病重总统的助手伪造了上月国家追加预算文件的总统签名。

President Umaru Yar'Adua has suffered ill-health for several years

They have written to the police asking them to investigate the forgery伪造，造假 claims.

The government said President Umaru Yar'Adua signed the budget despite being treated for a heart condition in Saudi Arabia.

Mr Yar'Adua has been away for six weeks, fuelling fears of a power vacuum真空 in Africa's most populous人口稠密的 nation.

Doctors say he is suffering from acute pericarditis急性心包炎 - inflammation发炎，炎症 of the lining⁷ of the heart. He also has a long-standing kidney complaint疾病，抱怨.

In a bid to dispel驱散，消除 fevered speculation推测，投机 over Mr Yar'Adua's health, ministers have insisted the president is recovering from treatment.

Information Minister Dora Akunyili said the president had spoken to his colleagues over the telephone on Tuesday.

Several court cases have been launched demanding that power be officially handed to the vice-president.

And one group of activists¹¹ has even suggested the president should be declared a missing person, and a search party should be sent out.

'Utter dismay'

In the latest move, an umbrella group for the main opposition parties known as the Conference of Nigerian Political Parties (CNPP) has demanded that the police investigate the alleged forgery⁵.

The group's lawyer, opposition official Femi Falana, said in the letter that the CNPP had tried to verify claims by the government that the budget had been taken to Saudi Arabia for the president to sign on his sick bed.

"To its utter完全的，彻底的 dismay沮丧，惊慌 our client (CNPP) has confirmed that the signature of the president and the seal of the Federal Republic of Nigeria were forged by some persons in the presidency," the letter read.

"Our client has instructed us to request you to use your good offices to set the engine in motion在运转中 for the investigation¹² and prosecution¹³ of those who carried out the nefarious邪恶的，不法的 act."

The CNPP said it would take the issue to the federal court next week if the police failed to act.

Mr Falana, who is also senior opposition activist¹⁰, is behind one of the court cases being brought against the government.

He wants judges to annul取消，废除 all decisions taken by the cabinet during the president's absence.

In the other cases, one activist wants Mr Yar'Adua to be sacked because of his ill health and the Nigerian Bar Association is demanding that power be handed over to Vice-President Goodluck Jonathan.

The courts have asked for the three cases to be merged¹⁶, and the consolidated¹⁷综合的，合并的 case is due to be heard next week.