LONDON, June 30 (Reuters) – Dry bulk fleet growth will keep freight rates under pressure into 2011 although there will be seasonal spikes, senior officials with leading ship broker Clarksons said on Tuesday.

Dry bulk freight rates have weakened in recent weeks due to softer demand by China for commodities, including iron ore and coal, and compounded by the pace of ship supply.

''It's still very volatile at the moment. I still think there is more downside before a late Q3 uptick,'' Henriette van Niekerk, director with Clarksons, told Reuters.

Van Niekerk said while seaborne trade would pick up in the third quarter, helped by better Chinese coal import demand and the start of the US grains season, the overall downward trend would last  ''very definitely into 2011.''

''The total dry bulk year-on-year demand growth potential is not matching the year-on-year expected fleet growth,'' she said in an interview.

Clarksons estimated dry bulk net fleet growth this year around 17 percent versus 10 percent in 2009.

''In order to fill up all those ships, a much more bullish economic outlook is required. Unless that can be obtained, which does not look possible at this point in time, freight rates will be under pressure,'' Van Niekerk said.

The dry bulk freight market has rebounded from record low levels seen in late 2008 due to economic turmoil which saw average earnings for the larger capesize vessels plummet to just over $2,000 a day, Baltic Exchange data showed. Average capesize earnings reached $24,237 a day on Tuesday.

Van Niekerk estimated average 2010 earnings for capesizes, which typically haul 150,000-tonne cargoes such as iron ore and coal, falling to $35,000 a day from $41,000 last year. She added that 2011 ''will be weaker than that.''

''I am optimistic about world seaborne trade growth but not to the extent that it can mitigate the dry bulk fleet growth over the next three years especially when the world is facing an economic downturn,'' she said.