Nairobi — The United States Monday revoked a visa of a minister for blocking reforms, sending a stern warning to the Grand Coalition Government to speed up implementation of Agenda Four.

Three more top government officials are to be barred from travelling to Washington, US assistant secretary for African Affairs Johnnie Carson said, and urged other countries to take similar action to up the pressure to avoid a recurrence of the December 2007 post election violence.

"Today (Monday), the US government has taken the decision to revoke the visa of a senior Kenyan government official who has been obstructive to reforms," he said.

Mr Carson, in what could send shivers down the spines of many ministers and prominent personalities, said the US had decided to focus on individuals within the government who were hindering reforms outlined in the National Accord.

"Not everyone in government is an obstacle to Agenda Four. We have focused our attention on individuals who have not used their offices well. We have had enough talk, we want action," he said at the residence of the US embassy in Nairobi flanked by Ambassador Michael Ranneberger.

He said he was delivering a message from President Obama and Secretary of State Hillary Clinton who he said had held meeting with chief mediator Kofi Annan and vowed to ensure that Kenya does not go down the path of bloodshed again come 2012.

It was significant that the US took the decision to bar a government minister even after President Kibaki wrote a letter to him last month protesting against America's decision to target members of the Cabinet. It was not clear whether Mr Carson carried with him a reply to President Kibaki's letter.

The protest letter to White House was written days after the US dispatched letters to ministers and senior government officials on both sides of the coalition warning they could be slapped with travel bans if they continued on their path of obstructing reforms.

On Monday, Mr Carson said: "We will not do business as usual with those who do not support reforms ... those who support violence. We are considering similar action with three other government officials and the paper work is moving fast."

He added: " This is a powerful signal be cause the individual cannot travel to the US for business or personal pleasure. The US is prepared to impose visa bans on those who stand against reforms. We hope other countries will follow."

Mr Carson tactfully warded off attempts by the journalists to give a clue to the minister in question stating that he had not been informed of the decision. "The individual is a senior government officials with influence. The name, and those of others will be made public soon," he said.

However, he said the individual affected by the travel ban has a US visa and travels widely on government duties. He urged the Kenyan leadership to heed local and international pressure to implement reforms that will end impunity, corruption and lawlessness.

Mr Carson spoke of international good will towards reforms and said Mr Annan had held talks with President Obama and Mrs Clinton in Washington on reforms in Kenya.

"Former UN secretary general has met in Washington with Secretary Clinton and President Obama and Kenya has featured in both meetings. They both have strong favourable views on Kenya," he said.

He then said: "We do not want to see Kenya return to the post election violence of early 2008. Reforms have to be implemented and we have our own interests that drive us."

He said a stable Kenya was good for the region and said that if violence breaks up again, the reverberations are felt as far as Kisangani in the Democratic Republic of Congo (DRC), Southern Sudan and other neighbouring countries in the region.