Burundi's embattled president skipped key regional talks Monday, staying at home to campaign for a controversial third term as a rebel general threatened to step up attacks.

Leaders of the five-nation East African Community (EAC) bloc had been due to meet Monday in the Tanzanian city of Dar es Salaam, but Nkurunziza instead sent his foreign minister.

Nkurunziza stayed in Burundi to lead his presidential campaign in the central Mwaro and Gitega regions.

Meanwhile rebel general Leonard Ngendakumana, who took part in a failed coup in May, has vowed further attacks until the government is overthrown.

"After we saw that we could not succeed our coup on May 15, we found it was necessary to keep fighting so that we can push Nkurunziza to keep thinking about what he is doing and maybe just resign," Ngendakumana told Kenya's KTN news channel in an interview broadcast late Sunday.

"All those actions that are going on in the country, we are behind them and we are going to intensify them until Pierre Nkurunziza understands that we are there to make him understand by force that he has to give up his third term."

The summit had been planned by East African Community leaders in attempts to find a solution to the crisis ahead of the July 15 presidential election. But there is a lot of scepticism on the ability of the regional bloc to resolve the crisis.

General Ngendakumana, a top intelligence officer, is an ally of coup leader General Godefroid Niyombare, who has been on the run since their attempt to seize power was thwarted.

Over 70 people have been killed in more than two months of protests, with almost 144,000 refugees fleeing to neighbouring countries.

Burundi held parliamentary elections last Monday, which were marred by running battles between protesters and the police resulting in the death of 20 people and several injured.

The polls were boycotted by the opposition, and the UN electoral observer mission said the elections took place "in a climate of widespread fear and intimidation". Results are yet to be released.

Presidential polls are due on July 15 followed by senatorial elections on July 24.

There are fears the current crisis could plunge the impoverished, landlocked country back into civil war.

During an EAC summit on May 13, army officers staged a failed bid to unseat Nkurunziza while the president himself attended the talks. Nkurunziza did not attend a second summit on May 31.

The EAC bloc includes Burundi, as well as Kenya, Rwanda, Tanzania and Uganda. But Rwandan President Paul Kagame, who has called on Nkurunziza to step down from power, is also not attending Monday's meeting, officials in Kigali said.

Host President Jakaya Kikwete of Tanzania, as well as Ugandan President Yoweri Museveni were due to attend, along with regional foreign ministers.