|Minor protests have continued on the streets of Abidjan|
The World Bank and African Development Bank say they will review their ties with the country following the "breakdown in governance".
The EU has warned the crisis threatens regional stability and has hinted that economic sanctions could be imposed.
A disputed election has left the country with two presidents, who have each named separate cabinets.
The BBC's John James in Abidjan says there are even rumours that two sets of ambassadors will be appointed, adding even more confusion to the situation.
Western nations have thrown their support behind Alassane Ouattara, who was standing as an opposition candidate in the 28 November poll.
Initial results from election officials gave him a clear victory over incumbent Laurent Gbagbo.
But the result was overturned by the Constitutional Council, which awarded the victory to Mr Gbagbo.
Our correspondent says both sides are firming up their positions, leaving little room for compromise.
In a joint statement, the development banks, which invest millions in projects designed to alleviate poverty, urged the politicians to break the impasse.
"We wish to continue working with the people of Ivory Coast in the fight against poverty but it is difficult to do so effectively in an environment of prolonged uncertainty and tension," they said.
"We will continue to closely monitor developments and reassess the usefulness and effectiveness of our programmes given the breakdown in governance."
Former South African President Thabo Mbeki is mediating in the crisis, which has sparked concern across the world.
On Monday, European Commission president Jose Manuel Barroso said the crisis risked stability and peace in the country and the region.
A spokeswoman for the EU's foreign policy chief, Catherine Ashton, said sanctions could be imposed if no solution was found.
International organisations and African leaders including Botswana's President Ian Khama have called on Mr Gbagbo to step down.
Mr Khama described the situation as a "real tragedy" and urged all African leaders to condemn what is happening.
"One would have hoped that by now, on the African continent, we would have gone past those days [of] coups and ridiculous situations like we have now in Ivory Coast," he told the BBC's Focus on Africa programme.
Small numbers of demonstrators took to the streets on Monday morning, and many businesses remain closed.
The military has announced that the country's borders have been reopened, days after they were closed amid fears of violence.
But Mr Gbagbo announced that a night-time curfew would continue for another week.
Several Western countries have advised their citizens not to travel to the country.
Belgium said it had deployed special forces personnel to protect its embassy in the country.
Ivory Coast was split in two during a civil war in 2002.
This year's presidential election was the culmination of years of peace talks between the government and the rebels movement which largely controlled the north of the country.
It was hoped that the election would help to reunify the country, but analysts say the result and subsequent impasse threaten to set the peace process back years.
Mr Gbagbo is a southerner and is popular in Abidjan; Mr Ouattara draws most of his support from the north.