By MacDonald Dzirutwe

HARARE (Reuters) - Zimbabwe has failed to pay the army on time for the second straight month, military sources said on Friday, underscoring the precarious financial position of President Robert Mugabe's government as it faces rare popular protests.

The military is paid on the 14th of the month but soldiers and air force officers said they were still to receive their pay and had not told when they would get it.

The delays could fuel political tensions in the southern African nation, which has been hit by drought, a drop in mineral prices and chronic cash shortages - all factors behind this month's protests against 92-year-old Mugabe.

"The mood is sour among the rank and file. Life is tough and we are not being told by our superiors whether we will be paid this month or not," one private told Reuters.

One colonel said: "We have not been informed of new pay dates by the ministry of finance."

There was no comment from finance minister Patrick Chinamasa, who was attending an African Union summit in Rwanda with Mugabe. Army spokesman Lieutenant Colonel Alphios Makotore could not be reached for comment.

DEFIANCE

There was a two-week delay in the June pay check for the military, a central security pillar throughout Mugabe's 36 years in charge of the former British colony.

Without balance of payment support and foreign credit, the government is seeking to clear $1.8 billion arrears to the International Monetary Fund, African Development Bank and World Bank in a bid to unlock new funding.

But the IMF said on Thursday it was still far from a financial program with Mugabe's government, which would need to resolve issues of governance, accountability, transparency and carry out economic reforms before receiving any cash.

Last week, a 'stay away' protest movement led by activist pastor Evan Mawarire shut down most businesses, government offices, schools and hospitals in the biggest act of public defiance in a decade.

Mawarire, who rallied followers under his #ThisFlag Twitter hashtag, was arrested this week and formally accused of treason but was freed on Wednesday when a magistrate threw out the charges.

Opposition leader Morgan Tsvangirai, who is suffering from cancer and who has so far stayed on the sidelines of the protests, pitched in on Friday, saying he backed Mawarire and other groups such as Tajamuka (We Refuse).

Tsvangirai said Mugabe should step down to make way for a transitional government to implement political reforms and plan fresh elections.

"I am giving President Mugabe an opportunity to soft land the national crisis. He will only have himself to blame if citizens take matters in their own hands. The ball is in his court," he told reporters.

(Writing by Ed Cropley; Editing by Joe Brock and Robin Pomeroy)