Foreign Secretary David Miliband has called on the leaders of Kenya's political parties to share power, as violence continues in the country.
Thousands have been displaced since the election on Sunday
More than 300 people have been killed in violent clashes following disputed presidential elections on Sunday.
Mr Miliband said President Mwai Kibaki and opposition leader Raila Odinga needed to take responsibility.
"The only way the country is going to make progress...is through the sharing of political power," he said.
The Kenyan Electoral Commission declared President Mwai Kibaki the winner after Sunday's election, but EU observers have said the presidential poll was flawed.
The United Nations says about 180,000 people have been forced to flee their homes because of the violence.
Mr Miliband, speaking on BBC Radio 4's World Tonight, said: "The truth is that the election shows that Kenya is split pretty fairly down the middle and the only way the country is going to make progress on the issues like the pitiless poverty... is through the sharing of political power.
"If that is coming on to the agenda, that is precisely what the unanimous view of the international community has been over the last few days and which we have all been working for."
He said "deep-seated problems" exposed during the week would not be tackled without such political compromise.
Mr Miliband said a re-run of the election was not necessary, but outlined three priorities: stopping the violence; documenting the irregularities of the election and making sure they were "pursued through legal and political means"; and mediation to "bridge the divide between the two sides".
He said the role of the president of the African Union, Ghana's President John Kufuor, "is absolutely critical to this."
Mr Kufuor has been unable to enter Kenya because he has not received an invitation from the Kenyan government.
"The message that has to go out loud and clear to both sides of the Kenyan political divide that they should be facilitating the entry of President Kufuor into the country as soon as possible," Mr Miliband said.
Earlier, International Development Secretary Douglas Alexander announced that £1m in aid would be given to Kenya,.
The money will be given to the Kenyan Red Cross for emergency humanitarian work after post-election violence flared across the country.
It will help provide food, shelter and clean water for as many as 500,000 displaced Kenyans.