By Hasmik Mkrtchyan

YEREVAN (Reuters) - Armed men holed up for almost a week at a police station in the Armenian capital refused to lay down their weapons after freeing their last four hostages on Saturday, instead demanding the resignation of President Serzh Sarksyan.

An unknown number of gunmen seized the police station last Sunday to demand the release of jailed opposition leader Jirair Sefilian. The gunmen killed one police officer and took nine others hostage, releasing two of them the same day and three more on Monday.

Demonstrators who gathered to show support for the gunmen's cause clashed with police outside the station on Wednesday, and Sarksyan has so far shown no intention of using force to end the stand-off, or of moving to free Sefilian.

The gunmen freed their remaining four hostages on Saturday, including Yerevan's deputy police chief and a national deputy police chief, after the authorities agreed to allow the media in to the police station grounds.

"We have no intention of laying down arms. This is the center of a free Armenia, and we want this atmosphere to spread over the whole of Armenia," Varuzhan Avetisyan, an activist in Sefilian's Constituent Parliament movement, told reporters, standing in the inner courtyard of the police station.

Avetisyan's statement was broadcast by several Internet sites and television. Several of the gunmen, at least some of whom are believed to be members of the Constituent Parliament movement, could be seen near Avetisyan in military uniform with Kalashnikov rifles.

Denouncing what he called widespread corruption and the dominance of the ruling Republican Party, Avetisyan said the main demand of his movement and of the gunmen was the resignation of the president, to be followed by new elections and the adoption of a new constitution.

"We will build a new state ... State institutions are not working here. You cannot move forward this way," said Avetisyan.

Sarksyan's administration was not available for comment.

Avetisyan's broadcast included a clip of an old man in a wheelchair who had came to the police station to call on his son, one of the gunmen, to leave the group and return home to look after him. But his son rejected his plea.

"I strongly love my father, but I also love my motherland. I demand Sefilian's release and Sarksyan's resignation," he replied in the broadcast.

Sefilian is accused by the authorities in the ex-Soviet state of plotting civil unrest. He was jailed in June on allegations of illegally possessing weapons.

A former military commander, he has accused Sarksyan of mishandling a long-running conflict between Armenian-backed separatists in the Nagorno-Karabakh region of Azerbaijan and Azeri forces.

A Moscow-brokered ceasefire halted four days of violence in the South Caucasus region in April, the worst flare-up in years, but sporadic shooting remains commonplace, causing fatalities.

Nagorno-Karabakh's defense ministry said one of their soldiers was killed and another wounded on Saturday in shooting. Azeri officials were not available for comment.

(Reporting by Hasmik Mrktchyan; Writing by Margarita Antidze and Dmitry Solovyov; Editing by Tom Heneghan and Hugh Lawson)