Censor.NET chief editor Yurii Butusov wrote on Facebook.
The move may be a first step for these political forces to merge into a single nationalist party for a joint participation in country's parliamentary elections, the journalist believes.
Butusov said the party leaders agreed they would not come up with any joint or personal statements before the march in order not to create the impression this is someone's private PR event.
Censor.NET spoke with the leaders of Svoboda and National Corps.
"The leaders of the three nationalist parties have decided to start the coalescence, firstly, with common activities, secondly, with the development of a common agenda, and only in the third place, with a founding meeting. We will try to figure out who we will engage and for what purpose. We hope other nationalist movements will get involved in the creation of a party," one of the National Corps leaders said.
"I think that in the near future, maybe in 1-2 months, we'll move on to real unification steps to stop any competition and create a single force.
"We are sure some 20,000-30,000 people will come tomorrow. This will be a test of our capacity. We'll put forward our demands to the authorities. The president, the government and the parliament share common responsibility. Our demands are split into social and political," the politician added.
The demands include:
- severance of relations with the Russian Federation;
- clear definition of the status of occupied territories and a ban on trade with occupiers;
- ban on the sale of land;
- rejection of the dictate of international financial institutions, which leads to the deterioration of social guarantees in Ukraine;
- ban on the sale of natural resources, in particular exports of round timber.
In turn, Svoboda member Andrii Ilienko said: "We deliberately wanted to avoid carrying out political rallies in the days of mourning and the anniversary of the massacre on Maidan. Feb. 22 is a day when Yanukovych fled Ukraine, so it is also a symbolic date to look back at the path the country has left behind. The demands of Maidan have been hardly met, the country needs a change.
"The nationalists must act as a united force. Becoming a single organization is out of question so far, but we have already begun to coordinate our actions, build up cooperation and form a common position.
"We are up against any 'special status' of the Donbas and elections in occupied territories, against the trade with occupied territories, against the privatization of strategic enterprises and the sale of land.
"The nationalists are certainly not going to resort to violence and warn security forces against inappropriate actions. We need to demonstrate a strong, high-quality organization. Our demands are a logical outcome of the demands of the Revolution of Dignity, and we will not surrender them."
Related materials: Occupied territories - Crimea and Donbas