LONDON ?-- The British government said on Wednesday one British national was missing and four others had been wounded in the series of bombings in Brussels on Tuesday which killed more than 30 people in one of the most horrific terrorist attacks on European soil in recent years.

The casualties of British citizens were revealed in a press release following an emergency cabinet meeting chaired by Prime Minister David Cameron to deal with the aftermath of the attacks.

"We are concerned about one missing British national and we are in close contact with the Belgian authorities. We are aware of four British nationals who were injured in the attacks -- three are being treated in hospital, one has already been discharged," a spokesperson was quoted as saying in the press release.

The British government has stepped up the security presence at a number of locations across Britain and will continue to do so in the coming days, while the national threat level remains at severe (an attack is highly likely) and the public are advised to be "alert but not alarmed," according to the press release.

The British government revised an earlier advice against travel to Brussels, but urged British nationals in Belgium to remain alert and vigilant, stay away from crowded places, and follow the instructions of the Belgian authorities.

Government departments in Britain observed a minute's silence at 11:00 am local time (1100 GMT).