The world's single largest donor to Burundi threatened to cut all aid to the African country if President Pierre Nkurunziza fails to renounce running for a third term despite violent protests.
The Belgian government issued the warning as two anti-Nkurunziza demonstrators were killed during unrest in the capital, Bujumbura.
The Foreign Ministry in Brussels said it hoped Nkurunziza will renounce a third term as this would "stain at the highest level the legitimacy of the Burundi executive and would make the completion of the bilateral programme impossible".
It also stressed that Belgium sent €47.4m (£33.6m, $52.7m) in direct aid to its former colony in 2013, making it the biggest bilateral donor.
Only two international organisations, the EU and the World Bank, provided more support to the country of 10 million.
Meanwhile, violence continued, sparked by Nkurunziza's decision to run for one term more than is allowed by the constitution.
The Red Cross said a demonstrator was shot dead and another person killed during clashes with police in Bujumbura's Musaga district.
Unrest escalated earlier in May as an army general announced a coup against Nkurunziza, taking advantage of the president's absence from the country. The takeover attempt was crushed within 48 hours but protests continued.
Nkurunziza's supporters argue the president's first term should not be counted as he was chosen by the parliament and not by the people in an election as is specified in the agreement.