* FTSE 100 index flat
* Set to post fourth straight month of gains
* Hits one-month high before easing
* Inmarsat falls ahead of FTSE reshuffle (Recasts, adds detail and quote, updates prices)
By Kit Rees and Atul Prakash
LONDON, May 31 (Reuters) - Britain's top share index was setto post its fourth straight month of gains on Tuesday, steadyingdespite a fall in satellite communications company Inmarsat ahead of a FTSE reshuffle later in the week.
The FTSE 100 index was flat in percentage terms at 6,268.66points by 1435 GMT, outperforming the broader European market.
While losses were broad-based, with ITV, StandardChartered and Kingfisher among the top fallers,shares in satellite company Inmarsat dropped 3.5 percentwith analysts citing the possibility of the firm being relegatedin Wednesday's FTSE 100 index reshuffle.
Inmarsat has fallen over 36 percent so far in 2016.
"Inmarsat's problem's are partly related to the sector, andpartly related to the oil price. Their clients are very largelymaritime, and maritime clients in turn are quite often linked tothe energy sector - it's just getting off its knees," KenOdeluga, market analyst at City Index, said.
The UK mining index also fell, down 0.3 percentas copper prices declined on a resurgent dollar followingincreasing expectations of a U.S. interest rate hike.
Copper prices remained on track for a more than 7 percentdecline in May, the biggest monthly drop since November.
St. Louis Federal Reserve President James Bullard on Mondayechoed remarks by U.S. central bank chief Janet Yellen thatglobal markets appear to be "well-prepared" for a summerinterest rate hike by the Fed, although he did not specify adate for the move. A stronger dollar makes commodities moreexpensive for holders of other currencies.
Shares in Glencore, BHP Billiton,Antofagasta, and Rio Tinto fell 0.2 to 1percent.
However, the commodity-heavy FTSE 100 index touched aone-month high of 6,290.07 points earlier in the session. It hasremained in positive territory this month and was headed for itsfourth straight month of gains.
"The FTSE 100 is still in the midst of sidewaysconsolidation, but with a welcome test of last week's 6,280ceiling and a close venture to 6,300," said Augustin Eden,analyst at Accendo Markets, adding that a drop towards 6,240would send a bearish signal for the index.
Among mid-caps, Alliance Trust rose 3.3 percentafter RIT Capital Partners made an informal mergerproposal for the investment firm. RIT confirmed talks saying amerger possibility was at "a very preliminary stage ofconsideration".
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Mike Dolan, Markets Editor EMEA. (Reporting by Atul Prakash; Editing by Richard Balmforth)
