Ukrainian opposition lawmakers have demanded an explanation from authorities after the arrests of several dozen activists who were blocking trade with eastern areas held by Russia-backed separatists.
The blockade began in January and has mainly disrupted rail shipments of coal that is mined in separatist-held territory and fuels power plants elsewhere in Ukraine.
Activists and lawmakers who support the blockade say coal sales have funded the separatists' war against government forces, which has killed more than 9,750 people in eastern Ukraine since April 2014.
Ukraine's main security agency, the SBU, said that it arrested 43 "blockader" activists at three sites on March 13 after they refused to surrender weapons.
Opposition lawmakers demanded answers from President Petro Poroshenko, the Interior Ministry, and the SBU on March 14 over the detentions.
Lawmaker Semyon Semenchenko wrote on Facebook that security forces dismantled the activists' makeshift camp and cordoned off the area on March 14.
The blockade remains intact in at least two other parts of the Donetsk and Luhansk regions.
Deputy parliament speaker Oksana Syroyid said the activists were released early on March 14.
Legislatures in the western cities of Rivne, Volyn, and Ternopil held what they said were emergency meetings on the detentions on March 14.
Activists staged a protest rally in central Kyiv attended by about 500 people on March 13.
The blockade has causing power shortages and added to the troubles faced by Ukraine's economy, which is drained by the war against the Russia-backed separatists.
The disruptions prompted Poroshenko to declare an emergency in late February and to urge all Ukrainians to try to conserve energy.
The separatists have threatened to stop supplying coal to the government in Kyiv or companies that are not in separatist-controlled areas.