By Patrick Nduwimana

BUJUMBURA, Oct 23 (Reuters) - Nearly 30,000 primary school teachers in Burundi began a week-long strike on Tuesday, accusing the government of failing to deliver better pay and conditions promised to them five years ago.

The teachers joined thousands of colleagues from secondary schools who are now in the third week of their own strike.

"We decided to strike because none of our claims have been implemented," Chantal Nahishubije, head of one of the country's three primary school teachers' unions, told reporters.

"If there is no development, we will keep on striking."

Teachers account for nearly three-quarters of all Burundi's civil servants, and earn between $25 and $35 a month.

The government has pledged to boost public employees' salaries by up to 34 percent by next year, but the International Monetary Fund has urged the authorities to raise revenues first.

Donors have promised millions of dollars for development in the small central African nation, which has been ravaged by more than a decade of civil war.

But some remain reluctant to disburse funds before seeing improvements in governance and human rights.