Hajder said earlier that Ukrainian officials had assured him the source of the oil pollution had been contained.
Schools in the Balti area have moved to online learning, while authorities focus on delivering tankers of drinkable water to the local population.
Maia Sandu, Moldova’s pro-European president, has been a strong supporter of Ukraine since Russia’s full-scale invasion in February 2022, praising Kyiv for protecting her own country from attack.
She has said Russia “bears full responsibility” for the oil pollution.
Russia has long accused Sandu of being “Russiaphobic”. She won a second term as president of Moldova in 2024 despite what the EU called “unprecedented interference [in the election] by Russia”.
Moldova has a population of 2.4 million, but Russia still has a military base in the Russian-speaking, breakaway region of Transnistria, which lies along much of Moldova’s eastern border with Ukraine. Local TV reports say oil has been spotted in Transnistria although officials there do not expect to impose restrictions on drinking water.
Meanwhile, Moldovan police have said an “active” Russian drone, armed with an “explosive device”, has landed 500m (1640ft) inside the Ukraine-Moldova border in the village of Tudora.