A three-member Lebanese parliamentary bloc resigned Saturday in protest at the Beirut blast widely blamed on government negligence and corruption, bringing to five the number of MPs to quit since the disaster.

In an emotional speech during a funeral service for one of his top party officials who died in Tuesday's blast, Samy Gemayel announced his resignation and that of the two other MPs from his Kataeb party.

"Your comrades took the decision to resign from parliament," Gemayel said, addressing Kataeb secretary-general Nazar Najarian, one of the 154 confirmed victims of the explosion at Beirut port.

Gemayel criticised the reactions of several top politicians who argued the international aid effort following the disaster would be an opportunity to break the diplomatic isolation of Lebanon.

"A new Lebanon must be born on the ruins of the old one, which you represent," he said, addressing the authorities at large and their clan leaders.

The Christian party's three resignations from the 128-seat parliament come after those of Marwan Hamade from the party of Druze leader Walid Jumblatt and independent MP Paula Yacoubian.

Yacoubian told the CNN news channel that she was urging the entire parliament to stand down. "As the MP of Beirut, I took the decision of resigning because I feel I'm a false witness in this parliament," she said. "There's nothing we can do, the decision-making is outside the parliament," she said. "Everyone should resign."

Lebanon's ambassador to Jordan also resigned in the aftermath of the blast, caused when fire spread to a depot where a huge amount of ammonium nitrate had been stored for years, unsecured. Early evidence shows top officials knew of its presence at the port and that safety procedures were knowingly and repeatedly violated.

The government has promised a swift and thorough enquiry but public trust is low that an investigative committee chaired by top officials will uncover the real culprits.