Why does Indian bitcoin exchnages are offering huge spread and why not international exchanges(ex:bitstamp,btc-e)
Both Bitstamp and BTC-e are international exchanges that focus on worldwide customers. Because of that, the market is much larger and more liquid and the spreads are more narrow. However, none of these exchanges will convert rupee (INR) or provide local deposits and withdrawals.
The local bitcoin exchanges do significantly less volume, so they have to charge a bit more. In addition, they provide services such as bid/ask in INR and integration with local Indian banks.
As more competition comes to the local exchange market, spreads will likely narrow, but still not match a Bitstamp or btc-e.
Even within a single exchange, different coins usually have very different spreads. Take a look at cryptsy: some coins have an enormous spread (10% - 20% of their value, e.g. UNOcoin, 42coin, etc.) whilst in others the sell/buy orders differ by just 1 or 2 satoshis (Dogecoin and to a lesser extent Litecoin).
The reason is the same in all cases: volume. The more buyers/sellers there are in a market, the higher the possibilities at least someone will go for a smaller profit and grab/get rid of a coin when they want it rather than when/if the market reaches the ideal price. So desperate buyers/sellers try to out-compete each other until the price more or less stabilizes at the point of minimum profit for all.
If there are no strong barriers to rapidly buying from an international exchange to sell at those Indian ones and/or vice versa, you could try making a profit from such differences - that's actually what happens at the biggest exchanges such as Mt. Gox, BTC-e, etc. which causes the prices at each to rapidly reflect the changes occurring at the others.