LISBON, Sept. 14 (Xinhua) -- Standard & Poor's has upgraded the Portuguese public debt rating from "stable" to "positive" and kept the rating at BBB-, the agency said in a statement on Friday.

"We expect the Portuguese economy to grow close to 2 percent per year by 2021, with the budget deficit improving to 0.4 percent of Gross Domestic Product (GDP) in 2020, by 0.7 percent this year," S&P said.

This update reflects confidence in the sustainability of progress recorded in the evolution of the Portuguese economy and in the management of public accounts, the Portuguese Finance Ministry said in a statement.

"The government intends to reach a balanced budget next year and to maintain the downward trend in the weight of public debt in GDP, in order to strengthen the resilience of public accounts and the Portuguese economy," said Finance Minister Mario Centeno.

According to Bank of Portugal, the ratio of Portuguese public debt to GDP fell significantly in the second quarter of this year, which stood at 125.8 percent at the end of June, down from 126.4 percent at the end of March.

The Portuguese government's debt-to-GDP ratio target for 2018, established in the Stability Pact agreed in April, is for a further reduction, to 122.2 percent.