Besides the Indian centre, the threat letter has been sent to the Belfast Islamic Centre and the Polish Association, reports from Belfast said.

The letter, threatening of racist violence, from the youth wing of the Ulster Defence Association warned: "No sympathy for foreigners, get out of our Queen's country before our bonfire night (July 11) and parade day (July 12).

"Other than that your building will be blown up. Keep Northern Ireland white. Northern Ireland is only for white British."

Patrick Yu, executive director at the Northern Ireland Council for Ethnic Minorities (Nicem), said race-hate crime had grown steadily in Northern Ireland recent years, with increasing incidents of assaults, intimidation, harassment and robberies.

Belfast has a small Indian community comprising entrepreneurs and professionals, including prominent businessman and consul-general of India, Lord Diljit Rana.

Some Indian IT companies also have a base in Belfast and other cities in Northern Ireland.

The Indian centre in Belfast is a voluntary organisation which was established in 1981 in the Carlisle Methodist Memorial Church Hall. The centre works towards the promotion and greater understanding of Indian culture and traditions in Northern Ireland.

It has long been a hub for arts and cultural activities for the Indian community in Northern Ireland, and has always sought to include the wider community wherever possible.

The centre which is also an information point for the Indian community, and is a regular point of contact, runs many activities. It participates in the advocacy and representation of the Indian community at all levels.

Yu added that the extremists "just want to scare people" and discourage foreigners from feeling at home in Northern Ireland.