India hosted first International Stamp Exhibition in New Delhi in the year 1954 to commemorate centenary of first issue of India Postage stamps, popularly known as India 1854 Lithographs.
There were two known 'essays' (surfaced in an oversees action house catalog) claimed to be prepared
for the "Centenary Stamp Exhibition 1954" but never issued postally, which had Flag motifs along with a facsimile of the Half Anna litho of 1854.
The set of four stamps issued officially on the occasion by the Indian Post & Telegraph Dept.
Publicity slogan post mark provided from large post offices before and during the exhibition.
Later, The Stamp Centenary Exhibition was also taken to Bombay and Calcutta.
Official stamp issued to commemorate INPEX-82, the Fourth India National Philatelic Exhibition, New Delhi was very identical to the stamp essays of 1954.
Vietnam Commemorates INDIA 89 World Philatelic Exhibition, New Delhi.
The Uruguayan postal department has issued a stamp to commemorate the 150th birth anniversary of Rabindranath Tagore. The stamp was released by Vice President Danilo Astori along with Indian Ambassador R. Viswanathan in the presence of Foreign Minister Luis Almagro at a ceremony in the Foreign Ministry at Montevideo. The stamp, illustrates the portrait of Rabindranath Tagore, the flags of Uruguay and India and the logo of INDIPEX 2011.
Besides above, there are several postal issues viz. Postmarks, Special Cachets etc. depicting the Indian National flag.
Here are a few of them;
USSR-India Bilateral Stamp Exhibition, Yerevan,1982
SAARC PHILEX 96, SAARC Philatelic Exhibition, Colombo, 1996
Nepal Bharat Philatelic Exhibition, Kathmandu, 2004.
There were two known 'essays' (surfaced in an oversees action house catalog) claimed to be prepared
for the "Centenary Stamp Exhibition 1954" but never issued postally, which had Flag motifs along with a facsimile of the Half Anna litho of 1854. 
Later, The Stamp Centenary Exhibition was also taken to Bombay and Calcutta.
Republic of Korea commemorates PHILAKOREA 84, Seoul,the miniature sheet has the national flags of all the participating Nations
The Uruguayan postal department has issued a stamp to commemorate the 150th birth anniversary of Rabindranath Tagore. The stamp was released by Vice President Danilo Astori along with Indian Ambassador R. Viswanathan in the presence of Foreign Minister Luis Almagro at a ceremony in the Foreign Ministry at Montevideo. The stamp, illustrates the portrait of Rabindranath Tagore, the flags of Uruguay and India and the logo of INDIPEX 2011.
Besides above, there are several postal issues viz. Postmarks, Special Cachets etc. depicting the Indian National flag.
Here are a few of them;
PHILYMPIA 1970, The London International Stamp Exhibition, 1970.
USSR-India Bilateral Stamp Exhibition, Yerevan,1982
SAARC PHILEX 96, SAARC Philatelic Exhibition, Colombo, 1996
Nepal Bharat Philatelic Exhibition, Kathmandu, 2004.
