* British navy chief warns over Scottish independence
* First Sea Lord says maritime defences would be weakened
* Nationalists argue Scottish defence has suffered under London rule
LONDON, April 15 (Reuters) - Scottish independence would weaken Britain's maritime defences by splitting up bases, infrastructure and staff, the country's navy chief said, the first serving military boss to give a view on the consequences if Scots vote to break away in September.
Writing in the Daily Telegraph newspaper on Tuesday, Admiral George Zambellas said the nations that remained in the United Kingdom if Scotland left the three-centuries-old union would cope eventually but Scotland would feel a "deeper impact".
Scottish First Minister Alex Salmond faces increased pressure over defence issues in an apparently choreographed campaign this week ahead of the independence referendum scheduled for Sept. 18.
On Sunday defence and aerospace industries cautioned Scotland could lose its competitive edge because of uncertainty over the future of the currency and taxation..
A group of 12 retired military chiefs on Monday said moving to evict the nuclear submarine base from the Clyde River in the event of a "yes" vote would cost billions of pounds, cut thousands of jobs and create international resentment.
Defence Minister Philip Hammond will say in a speech to an electronics company in Scotland on Tuesday that shared defence forces provide "security and peace of mind" for the people of Britain and Scotland's bond with the rest of the United Kingdom is "precious".
He will also talk about the complexity of what he calls "protracted" negotiations on the future of nuclear-armed submarines should Scotland vote for independence.
WEAKEN BOTH NATIONS
Zambellas said he believed independence would "fundamentally change maritime security for everyone in the United Kingdom" and damage the heart of the navy's capabilities.
"While the continuing United Kingdom would eventually adapt and cope, the deeper impact would be felt in Scotland, which would no longer have access of right to the security contribution of one of the finest and most efficient navies in the world," he wrote.
"The effectiveness of the Royal Navy, following separation, would weaken the security of both nations."
As well as being the home for Britain's four Trident nuclear-armed submarines, the Royal Navy has 16 ships and submarines and two commando units based in Scotland that employ about 5,250 people.
The Scottish National Party (SNP), which runs Scotland's devolved parliament, has promised to negotiate to maintain all military bases in Scotland if there is a Yes vote in September and before independence in March 2016.
After 2016, the party has vowed it would remove and ban all nuclear weapons in the first parliament of independence, which would mean the sure eviction of the Clyde River base, with the rest to be negotiated.
The argument for independence is that Scotland will be better off making decisions on its own - including about its considerable energy resources - rather than have policies dictated by London.
SNP defence spokesman Angus Robertson said Westminster was to blame for a multi-billion-pound defence underspend in Scotland and the loss of more than 11,000 jobs in the last decade.
"Under Westminster, Scotland has nuclear weapons that we don't need or want but not the naval vessels and marine defences that a nation with our size of coastline and strategic position should have," Robertson said in a statement.
"A Yes vote this year will ensure that decisions on Scotland's defence are made in Scotland, and always reflect the needs and interests of people in Scotland." (Editing by Sonya Hepinstall)