Hungary will build a 4-metre-high fence along its border with Serbia to stem the flow of illegal migrants, Reuters cited Foreign Minister Peter Szijjarto as saying on Wednesday. "Immigration is one of the most serious problem facing the European Union today," Szijjarto told a press conference. "The EU's countries seek a solution... but Hungary cannot afford to wait any longer." "We are talking about a stretch of border 175 km (110 miles) long, whose physical closure can happen with a four-metre high fence. The interior minister received an instruction to prepare that.," he added.