China's premier has described his four-day visit to India as historic saying it had produced "rich results".
Both sides signed several agreements during the visit
Wen Jiabao was speaking a day after India and China signed an agreement aimed at resolving a long-running dispute over their Himalayan border.
Both countries also set a target of increasing their annual trade to $30bn by 2010.
The world's two most populous countries fought a bitter war over their largely unmarked border in 1962.
"India, China are brothers," Wen Jiabao told journalists in Delhi on Tuesday.
"We want to elevate the strategic relationship."
He also said that China attached great importance to India's role in international affairs.
"India is a very populous country and is also a very important developing country.
"We fully understand and support the Indian aspirations to play an even bigger role in international affairs including in the UN," the Press Trust of India quoted him as saying.
India is lobbying to be included as a permanent member of an expanded UN security council.
On the final day of his visit, two of China's largest telecoms firms announced multi-million dollar contracts to supply equipment to India.
ZTE has won an order worth $208m (£110m) to provide 500,000 broadband lines to India's Atlas Interactive.
And Huawei Technologies has secured a three-year $70m deal to supply network equipment for both fixed line and mobile services to HFCL Infotel.
Indian and Chinese officials said on Monday that they had worked out a roadmap for resolving the disputed 3,550km (2,200 mile) border.
But analysts say both sides have a long way to go.
"Without a precise understanding of where the [border] lies, it would be difficult to go very far," says analyst Manoj Joshi in the Hindustan Times newspaper.
China wants to tap into India's software expertise
"It will be clear within the year whether the Chinese mean business on the border."
India's information technology industry has also reacted cautiously to China's call for closer cooperation.
During a visit to Bangalore Wen Jiabao said, with India's strength in software married to China's hardware skills, the two could launch the "Asian century" of information technology.
But Indian IT business leaders say legal issues, language and cultural barriers stand in the way.
"Obviously the main issue is one of the legal structure," Subhash Menon of Subex Systems told the AFP news agency.
"One is not sure at this point of time whether contracts with the Chinese firms will have legal protection."
Virendra Agarwal, director of India's fourth largest software exporter Satyam Computer Services said China was not a straightforward country when it came to business.
"You cannot pull out money or transfer it easily," Mr Agarwal, whose company has three offices in China, told AFP.
"Language is a barrier to an extent. But they are catching up."
As part of Monday's agreement China formally recognised the tiny state of Sikkim as part of India.
Until now, China had never recognised India's 1975 annexation of Sikkim.
Both sides have previously claimed the other is occupying parts of its land.
While India has accused China of occupying territory in Kashmir, Beijing has laid claim to territory in the north-east Indian state of Arunachal Pradesh.
The Chinese premier is on the final leg of his first South Asian tour since taking office last March.