The African Union Commission chairman has urged Kenya's government and opposition to reach an agreement to end weeks of post-election violence.
There were more violent clashes in Nairobi on Thursday
Jean Ping said he hoped for a deal next week. Earlier, there was hope that the rivals would end their talks on Friday.
A draft plan would involve creating a prime minister's post to be held by the oppositions, but disagreement remains over what powers this post would have.
The East African Community says the
crisis is hurting the regional economy.
"The weekend will be crucial. We hope that next week we'll have something which can be agreed," Mr Ping said in Nairobi.
Mediator and former UN Secretary General Kofi Annan said Thursday's agreement on the creation of a prime ministerial post showed progress towards ending violence.
But earlier hopes that a final deal would be announced on Friday proved unfounded as disagreements remained between the two sides on the exact role of the proposed prime minister.
The post is likely to be held by opposition Orange Democratic Movement (ODM) leader Raila Odinga, whose party demands that the post include executive powers.
The government favours "a non-executive prime minister but with some substantial meaningful responsibilities," government negotiator Mutula Kilonzo said, according to the AP news agency.
Foreign Minister Moses Wetangula told the BBC the delays were because "new things keep coming up."
"It's never over till it's over," he said.
Friday's round of talks started late after the government delegation failed to arrive on time.
Also on Friday, Mr Odinga flew out of Kenya to an unconfirmed destination. He is however keeping in close contact with his negotiating team at the talks, his aides say.
The East African Community has warned of an economic slowdown throughout the region as a result of the Kenyan political crisis.
"Trade flows have been negatively affected and so have exchequer and business revenues," EAC Secretary General Juma Mwapachu said in a statement on Thursday.
"We can only promote and attract investments sustainably, as well as assure effective intra-regional trade, if we have enduring peace and stability."
The landlocked economies of Uganda, Rwanda and Burundi, South Sudan and eastern Democratic Republic of Congo, largely rely on trade through the Kenyan port of Mombasa.
The opposition alleges widespread rigging in the December election, and international observers said the poll was flawed.
The Kenyan opposition said on Wednesday it would resume mass protests if a deal was not reached within a week.