NEW DELHI (Reuters) - India's new government kicked into gear this week, clearing billions of dollars worth of long-delayed defence projects, including a big navy base, as well as approving the scaling-up of one of the country's biggest dams.

The decision to give the projects the go-ahead despite concern about their environmental and social impact signals Prime Minister Narendra Modi's no-nonsense approach to issues he considers to be important for national security.

The clearances were made over several days and were the first major decisions from the government that swept to power on May 16 on promises of getting Asia's third-largest economy moving and building a stronger country.

Environment Minister Prakash Javadekar said the government could not compromise on efforts to build military and civil infrastructure on the border with China as well the west-coast naval base in as an alternative to crowded Mumbai port.

As well as the US$2 billion (S$2.5 billion) extension to the Karwar base in the southern state of Karnataka, Mr Javadekar approved a radar station in the Andaman and Nicobar islands in the Bay of Bengal.

A defence source said he also planned to fast-track road building along the disputed border with China.

Mr Javadekar said China had built infrastructure in the Coco Islands, which are controlled by Myanmar and just to the north of the Andamans. "If you have a situation where China is sitting in front and we won't do anything, how can you run the country like this," he said in comments made available to Reuters on Friday.

The radar station proposal had earlier been turned down because the Environment Ministry under the last government saw a threat to the Narcondam Hornbill, an endangered bird species.

The radar on Narcondam island is one of 18 that the military has planned, running north to south along the Andamans, which straddle the strategic seaway leading to the Malacca Straits.

This year, India's patchy radar meant it was unable to say whether missing Malaysia Airlines flight MH370 had passed over the islands.

Mr Modi met China's Foreign Minister this week and is likely to visit Beijing this year, but he is also keen to quickly build up border defences that have fallen far behind India's neighbour.

The 63-year-old's first foreign foray will be on Sunday to tiny Bhutan, a Himalayan buffer between India and China that has long been a close Indian military and diplomatic ally.

Mr Modi's Bharatiya Janata Party has promised to end a prolonged period of paralysis at the Defence Ministry where weapons acquisitions and infrastructure contracts were frozen because of fear of corruption scandals.

Mr Javadekar said he had also cleared the second phase of a naval base in Karwar, on the west coast, that had stalled because environmental activists had warned the ecology of the Western Ghats mountains would be affected.

The base is intended to take the load off Mumbai port, used by the navy and civilian ships. The navy has also said it wanted a more secure base to berth its latest aircraft carrier. "Mumbai is a target. We need an alternative. It is of strategic importance," he said.

The Environment Ministry is also trying to fast-track roads and defence projects classified as strategic.

Radars and telecommunications projects within 100km of the 4,000km border with China, large parts of which are disputed, will be put on an automatic approval list, a defence source said.

As well as the military projects, the government on Thursday approved a long-stalled proposal to raise the height of the Narmada dam to 138.73m, from 121.92m, so more water will be available for drinking, irrigation and power generation.

The project will benefit Mr Modi's home state of Gujarat. As chief minister of the state, he campaigned for approval to build the dam higher to protect farmers from drought.

Activist Medha Patkar, who has long campaigned against the project, said about 250,000 people will be displaced.

She said the government appeared to have rushed into the decision without looking at the social and environmental impact as required by law. "How could the government deal with such a grave situation and go ahead just because Mr Narendra Modi is the prime minister?" she said.