A DR Congo opposition bloc called Thursday for a nationwide stoppage and police clashed with demonstrators in two eastern cities after upcoming elections were placed on hold in their region.

Lamuka, a coalition of parties supporting opposition candidate Martin Fayulu, called for cities to be brought to a standstill on Friday, two days before polling day.

A diplomatic storm with the European Union meanwhile erupted into the open as the government demanded Brussels withdraw its envoy to Kinshasa within 48 hours, a call the EU said was "completely unjustified".

Read more: DR Congo gives EU 48 hours to withdraw envoy

Delayed several times, the election will be the Democratic Republic of Congo's first presidential ballot in seven years.

But on Wednesday, the national election panel announced the vote would be postponed in several troubled areas until March.

Even so, the vote will continue to take place in the rest of the country as scheduled on December 30, and the next president will be sworn in on January 18, it said.

In the eastern province of North Kivu, the region most affected by the delay, several hundred demonstrators gathered on Thursday in the administrative district of the city of Beni.

Gunshots were heard over a roughly hour-long period.

In Goma, the provincial capital, demonstrators set up barricades in the districts of Majengo and Katimbo and at the entrance to the university.

This year's Nobel peace laureate Denis Mukwege, hailed by several thousand people on Thursday on his return to the country, urged the authorities "to respect the constitution."

"The electoral process is at an impasse," he warned.

The vote should have been held in 2016 when President Joseph Kabila, in power since 2001, reached a two-term limit set under the constitution.

But he remained in office, invoking a caretaker clause under the constitution, but also triggering protests.

Opposition anger

Legislative and municipal elections are being held at the same time as the presidential poll.

The latest postponement applies to the cities of Beni and Butembo in North Kivu, as well as to the territory of Yumbi in the southwestern province of Mai-Ndombe.

Around three percent of some 40 million registered voters will be affected by the delay.

But opposition parties described the delay as a ploy to gag a stronghold of support.

At a press conference, Lamuka called for cities around the DRC to be brought to a standstill on Friday but said it would still contest the poll.

The other main opposition party, the veteran Union for Democracy and Social Progress (UDPS) "condemned" the new delay but also said it would not boycott.

Wednesday's announcement by the Independent National Election Commission (CENI) blamed militia violence and an outbreak of Ebola in North Kivu, and inter-communal clashes in Yumbi.

It is the fourth delay to strike the elections. They were postponed in 2016 and 2017 and then moved from December 23 to December 30 after a warehouse fire destroyed election equipment.

Presidential challenge

Three men are heading a field of 21 candidates in the presidential race.

They are Kabila's hand-picked successor, Emmanuel Ramazani Shadary, a hardline former interior minister; Fayulu, a little-known legislator and former oil executive; and UPDS chief Felix Tshisekedi.

A festering row with the EU over Shadary burst into the open on Thursday.

Foreign Minister Leonard She Okitundu gave the EU 48 hours to withdraw its representative, retaliation for sanctions against Shadary and 13 other officials for cracking down on anti-Kabila protests.

The sanctions, imposed in early 2017 and extended on December 10, comprise a travel ban and asset freeze for "obstruction of the electoral process and... related human rights violations".

An EU spokesman said that the bloc "regrets this decision and considers it as completely unjustified", adding that it "can only be considered counterproductive".

It has not had a peaceful transfer of power since gaining independence from Belgium in 1960.

In 1996-1997 and 1998-2003, the DRC became the theatre of two wars that left millions dead, many homeless and sucked in countries from around central and southern Africa.

The UN and western powers have repeatedly urged the DRC to have peaceful, transparent and free elections, a call echoed on Wednesday by the presidents of Angola, Botswana, Namibia, Zambia and the neighboring Republic of Congo.

(Front image: Protesters sing the Congolese national anthem around a roundabout in Beni during a demonstration against the postponement of elections in the territory of the Beni and the city of Butembo, December 27, 2018. /VCG Photo)