* Opposition questions oil strategic fund usage
* Angola economy to struggle due to oil price dip
* Govt sources - national budget audited by global lenders (Adds comments from govt sources)
By Herculano Coroado
LUANDA, Oct 20 (Reuters) - Angola's main opposition political party has asked President José Eduardo dos Santos to explain why the state was not using strategic oil funds from oil revenue to help the ailing economy in its response to last week's state of the nation address.
Angola's Vice President Manuel Vicente said last Thursday the economy will grow more slowly than expected this year, as subdued oil prices sap public spending, hobble the currency and push up debt levels in Africa's second largest crude exporter.
Vicente, who was delivering the state of the nation address in the absence of President Jose Eduardo dos Santos, said sub-Saharan Africa's third largest economy would grow four percent this year, down from a previous forecast of six percent.
Isaias Samakuva, president of UNITA (the National Union for the Total Independence of Angola) said Angola had strategic funds reserves from his oil revenue from 2011.
Samakuva said an estimated $130 billion in strategic oil reserves had been saved up over the years, but wondered why the money was not being used to cushion the economy. Samakuva did not disclose the source of his estimates.
"There is a lot of money from oil that was saved when the price of oil was in high and the administrator of that money saved is not to say where is this our money," Samakuva said in a speech late on Monday.
An official at the Finance Ministry, who declined to be named, said the issue was political and not for the government.
"That is a political statement and should be responded by the ruling party or by President Dos Santos himself, and it should not be done at the ministry level," the official said.
A second source at the same department said: "If Samakuva is unsure about our transparency level, he should go to talk to the World Bank and the IMF about it, both institutions have made audits to Angola's national annual budgets and expenditures."
Angola's economy has come under persistent strain since oil prices LCOc1 more than halved last year. Angola relies on oil exports for two-thirds of tax revenue and 95 percent of foreign currency receipts.
Samakuva said Angola was facing one of the worst crisis since its civil war ended in 2003, with many investors including foreign business unable to send their dividends abroad owing to dollar shortages.
Luanda has cancelled plans for a $1.5 billion Eurobond due to challenging economic conditions and has not set a new time frame for the issue. (Writing by James Macharia)