Libya's interim interior minister said Saturday Tripoli could "facilitate" those people seeking to get to Europe illegally unless the European Union helps it combat the problem.

"I'm warning the world and Europe in particular -- if they do not assume their responsibilities, Libya could facilitate the transit of this flood" of immigrants towards Europe, Salah Mazek told a news conference.

Four Libyan protesters were killed and 20 wounded in Benghazi when gunfire erupted at a demonstration outside a militia base in the eastern city, security and medical sources said Saturday.

"Angry citizens, some of whom were armed, demonstrated around the headquarters of the February 17 Martyrs Brigade," an Islamist militia accused by residents of being involved in attacks across Benghazi, a security official said.

U.S. House Democrats remained divided Friday over whether to participate in the newly-created panel to investigate the Benghazi attacks of 2012, a probe Minority Leader Nancy Pelosi slammed as a "political stunt."

Democratic and Republican staffers huddled behind closed doors to thrash out the terms of the select committee that the House of Representatives approved Thursday in a party line vote.

Gunmen assassinated a top government intelligence official in Benghazi on Thursday, a day after a political leader in the flashpoint city of eastern Libya rejected the election of a new prime minister.

Colonel Ibrahim al-Senussi Akila, head of general intelligence in Benghazi, was shot dead near the Medical Center in the center of the Mediterranean city, a security source told AFP.

Libya on Monday confirmed the appointment of a new premier after a chaotic vote highlighting tensions between Islamists and liberals in a country sapped by violence nearly three years after the overthrow of Moammar Gadhafi.

The General National Congress, the interim parliament, ratified Ahmed Miitig, an Islamist-backed businessman, as prime minister in a decision signed by its speaker.

The speaker of Libya's General National Congress confirmed Ahmed Miitig as the country's prime minister Monday, after approving his appointment following a chaotic session of the interim parliament.

"Ahmed Omar Miitig was appointed head of the transitional government, and asked to form his cabinet and present it to the GNC for a confidence vote within 15 days," said the text of a decision signed by speaker Nuri Abu Sahmein.

U.S. Secretary of State John Kerry was slapped with a subpoena Friday by Congress's main oversight panel demanding he testify about how the Obama administration responded after a deadly 2012 attack in Benghazi, Libya.

House Government Oversight Committee chairman Darrell Issa announced the subpoena in a tweet, saying he requires that Kerry testify on May 21.

Jihadist gunmen stormed police headquarters in Libya's second city Benghazi before dawn Friday, sparking fighting that killed at least nine soldiers and police, government and medical sources said.

"Armed brigades of Ansar al-Sharia and other criminal groups attacked the complex with both light and heavy weaponry," a government statement said.

Republican lawmakers compared Barack Obama's White House to the secretive Nixon administration on Thursday, denouncing its response to the 2012 attack on a U.S. mission in Benghazi, Libya.

On Wednesday a conservative group published a White House email it had obtained after a legal challenge and which critics say shows an attempt to put a political spin on the deadly assault.

About 300 illegal immigrants abandoned by people traffickers in the scorching Sudanese-Libyan desert, where several died, will be escorted to a Sudanese town from Friday, the army said.

Army spokesman Sawarmi Khaled Saad told Agence France Presse the migrants, who were receiving medical care, would be taken by local Sudanese officials to the northern town of Dongola on the Nile River.