Apparently nursing a bizarre grudge against the Dutch electronics giant Philips, and disenchanted with the quality of widescreen TV, the man, who was 59, finally snapped, walked into a bathroom and shot himself in the head twice with an automatic pistol.

He had told police negotiators that he needed more time to consider his demands.

The man, whose identity has not yet been released, held 18 people hostage at the height of the siege while some 200 office workers found themselves trapped on different floors during the course of the day.

Police said last night that none of the hostages had been harmed and that they were sorry that the gunman had decided to take his own life.

The drama began yesterday morning when the man, armed with two pistols and an undisclosed quantity of explosives, calmly walked into the 35-storey Rembrandt Tower office block in the east of the city and swiftly took control of the building.

The Rembrandt houses a host of financial institutions and the significance of yesterday's date - the six months after the September 11 attacks on America - was not lost on terrified office workers.

It was not long before strange homemade posters began to appear in the windows of the building criticising Philips, which once had its headquarters there.

Soon afterwards, a Dutch TV company received a fax from the gunman complaining about the "arrogant manipulation by manufacturers of widescreen TV sets", accusing them of "creative nonsense".

A sign bearing the words "Kleisterlee lies" (Gerard Kleisterlee is the chairman of Philips) appeared, along with another saying "We mislead", in an apparent parody of Philips' advertising slogan "We Make Things Better".

Police later explained that the man felt that manufacturers had made wildly exaggerated claims about widescreen technology. Philips confirmed that the man had been in touch before to make his feelings known.

"We dealt with him like hundreds of thousands of other callers. We weren't threatened and there was no reason for us to contact the police," said a spokesman.

An official from the prosecutor's office said: "He didn't make any demands. He wanted attention for his problems with widescreen television. There were psychological problems involved."

Mark Herveys, one of the hostages, said that the man remained "extremely calm" throughout the siege.