Smoke was seen rising from the presidential palace amid heavy gunfire in Niger's capital, Niamey, on Thursday in an apparent coup attempt.
Political tensions have been high in the central African uranium exporting country in recent months over president Mamadou Tandja's extension of his rule, which drew widespread criticism and international sanctions.
"We can hear gunshots from time to time but ... the president is in his office," a security source inside the presidential palace told Reuters by telephone.
Witnesses said machine gun and heavy weapons fire erupted in the city at around 1200 GMT and that smoke was rising from the presidential palace. A Reuters witness later saw five injured soldiers at a hospital in Niamey.
An intelligence officer, who asked not to be named, said the violence was a coup attempt that the presidential guard was trying to put down. A French diplomatic source said the fighting appeared to have been short-lived.
"There was apparently an attempted coup d''etat," the diplomatic source said. "Shots were heard in the barracks of the presidential guard."
One diplomat had travelled across the city without seeing any military deployment, he said.
Police sources said they believed the attackers came from outside the city in armoured vehicles.
Another member of Tandja''s entourage in the palace said that "for now everything is alright".
The action was likely to be contained and Tandja retain power, said Control Risks analyst Rolake Akinola.
"It is likely that it happened quickly ... but it goes to show the political crisis is deepening. This indicates that there is growing discontent against Tandja, even in the loyalist camp," she said.
"We will see increased political and regional pressure for Tandja to concede (political) ground."
Several major resources firms have operations in Niger.
"We got confirmation on the ground that things were heating up, but ... we don't know if this affects some of our employees," said an official at one such firm, speaking on condition of anonymity.
Tensions high
Tandja drew criticism and sanctions after dissolving parliament and orchestrating a constitutional reform in 2009 that gave him added powers and extended his term beyond his second five-year mandate, which expired in December.
The constitutional referendum in August, condemned internationally and at home, eliminated many of the remaining checks on Tandja's authority, abolished term limits, and gave him an initial three more years in power without an election.
The constitutional court declared that vote illegal, to which Tandja responded by abolishing the court and replacing its members with his own appointees.
West Africa's regional bloc suspended Niger in October and the United States terminated trade benefits for the country in December, while former colonial power France also criticised Tandja last year. France's foreign ministry was not immediately able to comment on Thursday.
Despite political turmoil and occasional Tuareg rebellions, Niger has attracted billions of dollars in investment from major international firms seeking to tap its vast mineral wealth, including France's Areva and Canada's Cameco.
French state-owned Areva, which has been digging uranium in Niger for decades, is spending 1.2 billion euros ($1.79 billion) on a new mine, and China National Petroleum Corp signed a $5 billion deal there last June.
Washington has denounced Tandja's actions as undermining the rule of law, while the European Union has delayed aid payments.
