Ivory Coast troops have deployed around a hotel housing Alassane Ouattara, the UN-backed winner of disputed presidential elections.
The troops loyal to incumbent President Laurent Gbagbo are facing UN-forces and former rebel soldiers protecting Mr Ouattara's headquarters in Abidjan.
Both Mr Outtara and Mr Gbagbo had declared themselves the winner of last month's election.
Reports that there have been clashes could not immediately be verified.
The forces loyal to Mr Ggagbo reportedly include members of the presidential guard and gendarmes in trucks mounted with machine-guns.
EU foreign ministers have agreed to prepare sanctions against Ivorian officials refusing to recognise Mr Ouattara as the country's new leader.
Sanctions would target "those who are obstructing the process of peace and national reconciliation, and in particular who are jeopardising the proper outcome of the electoral process", the ministers said in a statement on Monday. BBC News
