The death toll from severe flooding across Myanmar has risen to 88, officials said on Friday, as rising waters swallowed more homes in low-lying regions in some of the poorest parts of the country.

More than 330,000 people have been affected by torrential monsoon rains that triggered flash floods and landslides, cutting off communications as the deluge engulfed roads and destroyed bridges.

Residents have raced to bolster sand-bag defences along the Irrawaddy river in the southwest as floodwaters swell the mighty waterway, swamping dozens of villages as the waters drain from further north.

"Nothing like this has happened before, but I am not the only one suffering," said Soe Min Paing, a fisherman from Kyauk Taing village in Nyaung Don township, whose home has been inundated.

The death toll has risen to 88 from 74 on Thursday, according to Phyu Lei Lei Tun of the social welfare ministry, although this could climb again as relief teams reach isolated areas, some of which remain cut off more than a week after the disaster struck.

Impoverished western Rakhine state has suffered the highest number of fatalities so far, the state-run Global New Light of Myanmar reported, with at least 55 killed after Cyclone Komen tore across the Bay of Bengal last week.

The heavy monsoon downpours have caused devastation across large parts of South and Southeast Asia in recent weeks, claiming hundreds of lives and displacing millions.

In Myanmar, where 12 out of 14 states and regions have suffered flooding, international aid has stepped up in recent days following an official government request for help.

Myanmar's previous junta government was accused of indifference in its sluggish response to Cyclone Nargis in May 2008, a crisis which left nearly 140,000 people dead or missing.

The quasi-civilian regime which replaced outright military rule in 2011 has been eager to show it is mobilising.

But many of those affected by the flooding appear not to be relying on government help, either trying to cope alone or turning to local monasteries or community groups.

Authorities have insisted that crucial elections set for November 8 will go ahead despite the disruption caused by the floods even as they try to assess the scale of the damage.

More than 200,000 acres of farmland have been ruined and large numbers of animals killed as well as the thousands of homes lost, according to state media.

Fears are also growing over malnutrition as some of the worst-hit areas are among the country's poorest, according to the UN's World Food Programme.

"Thousands of people have lost homes, livelihoods, crops and existing food and seed stocks. Food security will be seriously affected," WFP Country Director Dom Scalpelli said in a statement.

In a statement released Friday the European Union announced the EU and its Member States would donate an extra 4.5 million euros ($5 million) in emergency aid to Myanmar in response to the government's appeal for international assistance.