The president of the European Council, Herman Van Rompuy, has urged Kosovo's president to do more to uphold the rule of law and fight organized crime and corruption to achieve the Balkan state's goal of joining the European Union.

Van Rompuy said Tuesday implementing reforms will “steadily bring Kosovo closer to the EU,” but warned the process will require “a lot of hard work, patience and focus.” He was speaking in Brussels at a joint news conference with visiting Kosovo President Atifete Jahjaga, who said Pristina is “ready and capable to fulfill all of its obligations” to become a member of the EU and the NATO alliance.

Van Rompuy expressed hope that Kosovo and the 27-nation EU bloc will make progress soon on starting a visa dialogue. He also urged Ms. Jahjaga to continue talks with Serbia to try to resolve remaining issues of dispute between the two. Predominantly ethnic Albanian Kosovo seceded from Serbia in 2008, a move Belgrade rejected.

The European Council president praised Kosovo and Serbia for reaching economic agreements last week in EU-mediated talks in Brussels. The agreements call for Serbia to recognize customs stamps marked “Kosovo Customs,” a move designed to facilitate trade and allow both states to lift embargoes on each other's goods.

A trade dispute between Serbia and Kosovo erupted into violence last month. Pristina sent troops to border crossings with Serbia to enforce a new ban on Serbian imports. The move was a response to Serbia's blocking imports with Kosovo's customs stamps. But local Serbs confronted the ethnic Albanian troops. One soldier was killed in the unrest. NATO peacekeepers intervened to stop the fighting and took over control of the border crossings.

On Tuesday, ethnic Serbs, who remain loyal to Belgrade, held a rally in the northern Kosovo town of Mitrovica. Hundreds of elementary and high-school students and their teachers joined protesters demonstrating against demands to abolish Serbian institutions in Kosovo. Protesters carried banners with messages such as “We won't give up Kosovo.”

Similar rallies were held in the towns of Zvecan, Leposavic and Zubin Potok.